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APRIL 1984 

VOL. 6 NO. 4 

$3.00 USA/S3.50 CANADA 

le realm of SCORPION an 



imagination be your guid< 

ie system 

With a complet^6502 microprocessor on for full interrogation and c 

board, SCORPION is ideal for experiments in artificial A 250-page manual contains detailed instructions for 

intelligence, pattern recognition, hardware and assembly and use. 

software development, mobile robot theory and ^^^©et^acquainted with SCORPION today, 

language development. Available now at computer stores and directly from 

Rhino Robots. 

RS-232C interface and power 
cord enter a 12-pin connector 
to serve SCORPION'S 
communication and power 

The computer card provided 
with SCORPION is assembled 
and tested in the factory prior 
to shipment to ensure ease of 

A CdS cell at the focus of the 
optical scanner gives the 
system the ability to recognize 
up to 127 different brightnesses 
in its environment. 

Controller can be easily 
expanded to run 2 additional 
motors (6 total) and provide 18 
more I/O lines 

A polished, chrome-plated 
parabolic optical antenna 
provides the gain necessary to 
give the optical scanner its 
viable sensitivity. 

Cover not shown 

2 small stepper motors allow 
movement of the optical 
scanner in horizontal and 
vertical modes Instructions 
provide the capability of 
resetting and moving each 
axis and making a scan along 
each axis 

$660.00 complete. 

FOB Champaign, Illinois. Shipping included on pre- 
paid orders. 

Manual only: $20.00 prepaid. 

Dealer inquiries welcome. 

Coming soon from Rhino Robots: Power supply, voice, 
memory expansion and sonic distance detecting 
modules . . . plus other SCORPION accessories. 



3402 N. Mattis Ave. P.O. Box 4010 
Champaign, IL 61820 

Circle 18 

A bumper is provided on each 
side of SCORPION. Each 
bumper has 2 microswitches 
that are actuated upon 
collisioa These 8 
microswitches give the 
on-board computer detailed 
information about which 
section of SCORPION has 
encountered an obstruction, 
thus allowing intelligent 
recovery to take place. 

Chassis made of uoir 
aluminum Entire system is 
punched out on CNC punches 
to insure accuracy and quality. 

Large 45" diameter molded 
wheels, driven by size 28 
stepper motors, provide 
powerful traction for 
SCORPION. Each wheel can be 
run at any of 70 speeds in 
either direction. 

mounted on the PC board 
below SCORPION, provide the 
ability to detect floor 
brightness and allow the 
system to be programmed to 
read codes and follow 
complicated paths 

SCORPION'S 2 eyes can be 
programmed to go on and off 
in any sequence to indicate 
intelligence, surprise or other 

Sog US of 

COffllMH/Spring ’84 

Atlanta, GA May 22-25, 1984 

A 2 diameter speaker, whose 
frequency and duration of 
tone can be controlled from 
the host computer, is provided 
at the front. The speaker can 
be used to make robot noises 
generate complicated sounds 
and play tunes 

SYSTEM FOR $250.00! 

Our board, the NMIX-0111, the “100 Squared,” 
surrounds the R65F11 with innovative circuitry that 
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system. All that is needed to do program development 
in FORTH is a CRT terminal or microcomputer that 
speaks RS232 (seven data, one start, two stop bits). 

Power comes from a 9 volt AC or DC power source. 
DC to DC converter provides negative voltage for the 
RS232. Three JEDEC 28 pin sockets are provided 
which will accept: 

RAM’s 2016,2128,5517,6116,5564 

EPROM’s 2716,2732,2764 

EEPROM’s 281 6A 

The board can program in circuit: 

R2816A 2764* 

* requires additional VPP voltage supply. 

Substantial Quantity Discounts 
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* FORTH kernel in ROM 

* 1 92-byte static RAM 

* 16 bidirectional, TTL-compat- 
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* Two 16-bit programmable 
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* Serial port 

* Expandable to 1 6K bytes of 
external memory 

* Now Available— New R65F12 Board 
Same as Above with 40 I/O Lines 

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(214) 642-5494 


New and Available now. . . 


Circle 16 

Hayden introduces you to... 


Welcome to the 21st Century Today- 
the age of robots! And your personal 
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These on-target titles will keep you in 
touch with all the advances being 
made today-and they'll show you 
just what to expect in the coming 

A series whose time has arrived. 


Order by Phone 
1 - 800 - 631-0856 

operator RA44 • In NJ (201) 393-6315 

Robotics Age: In the Beginning 

(Edited by Carl I Helmers) Chronicles the breakthrough 
discoveries that have made robots easier to build and 
practical for every day use. Many fascinating applications 
are described — robots as mechanical toys, welders, and 
even replacements for body parts. 

Edited from articles in Robotics Age. 

# 6325 , $ 16.95 

Artificial Intelligence 

(Stevens) Provides a comprehensive understanding of 
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Working Robot 

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Android Biography 

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Mail to: 

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10 Mulholland Drive • Hasbrouck Heights, NJ 07604 

Please send me the book(s) indicated below by code number. If I am not 
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Signature Residents of NJ and CA must add sales tax. Prices subject to change. 

Circle 7 

Publisher/Editorial Director 
Carl T. Helmers, Jr. 


Raymond GA Cote 

Technical Editor 
Roberta Toth 

Consulting Editors 
Walter R. Banks 
Russ Adams 

Projects Editor 
Heidi Copeland 

Nancy Estle 

Production Assistant 
Tobee Phipps 

Circulation Manager 
James E. Bingham 

Dealer Accounts 
Linda Thren 

Circulation Assistants 
Margaret Dineen 
Brian Warnock 

Velma Perkins 

Maryellen Kelly 

Copy Editor 
Freida C. Day 

Cheryl Wilder 

Advertising Manager 
Donna Louzier 

Advertising Sales 

Southeast, Midwest, West 
Elizabeth S. Alpaugh 
Edith Crabtree Barrett 
Robotics Age Inc. 

174 Concord Street 
Peterborough, NH 03458 

Mid-Atlantic, Northeast 
CEL Associates, Inc. 

61 Adams Street 
Braintree, MA 02184 

ROBOTICS AGE— (ISSN 0197-1905) is published monthly by 
Robotics Age Inc., Strand Building, 174 Concord Street, Peter 
borough, NH 03458, phone (603) 924*7136. Address subscrip- 
tions, change of address, USPC Form 3579, and fulfillment ques- 
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Air delivery to selected areas at additional charges, rates upon 
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Address all editorial correspondence to the Editor at Robotics 
Age, Strand Building, 174 Concord Street, Peterborough, NH 
03458. Opinions expressed by the authors of articles are not 
necessarily those of Robotics Age. To aid in preparation of ac- 
ceptable articles, the Robotics Age Authors' Guide is available 
upon request if accompanied by a self-addressed 8V2 by 11 inch 
envelope with first class postage for 3 ounces. Unacceptable 
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addressed envelope with sufficient first class postage. Not 
responsible for lost manuscripts or photos. 

Each separate contribution to this issue, and the issue as a 
collective work, is © 1984 Robotics Age Inc. All rights reserved. 
Copying done for other than personal or internal reference use 
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quests for permission should be addressed in writing to Robotics 
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APRIL 1984 VOL. 6 NO. 4 


4 A Robot is a Robot is a Robot by Joseph Engelberger 


15 Closing the Sensor- by R. Andrew Russell, Ph.D. 

Computer-Control Loop 

Sometimes, the simplest of sensors can produce a dramatic result. 
Modelled from the cats’ whiskers of nature, these experimental touch 
sensors close the loop for a robot arm. 

21 Bipedal Balance by Thomas A. Easton 

An understanding of how living bipeds maintain their balance 
provides design ideas for constructing bipedal machines. 

27 Patent Probe: by Russ Adams 

Robot Warehouse 

Jeeve, go get box number 33 and send it to assembly station 10! 
The ultimate in materials handling is the robot warehouse. See one 
approach described in Patent #4,395,181. 

29 Armega 33 by D. F. Boyd 

Part II: The Electrical Components 

A look at Armega 33’s electrical and electronic control components. 


6 Calendar 37 Classified Advertising 

13 Letters 41 New Products 

26 Advertiser Index 

About the cover: Shiva, the cat, in R. Andrew Russell’s article was the inspiration for 
this month’s cover by Robert Tinney. Robert has caught the essence of how we can 
mirror nature’s methods with our applied technology. 

BPA Membership (SMA Division) Applied for, August 1983 

ROBOTICS AGE March 1984 3 

Personal Robot 

ALBUQUERQUE, NEW MEXICO April 13-15, 1984 


IPRC '84 will offer an opportunity for robot enthusiasts to display 
their creations and enter them in various competitions. There will 
also be commercial exhibits and seminars on personal robots, as 
well as cultural events portraying the history and mythology of 
personal robots. 

The Congress will open with a major ceremony — an event com- 
plete with dignitaries, limelight, media, robots and fanfare. The 
Congress will close with an Awards Brunch recognizing the 
individual achievements of the Personal Robot Developers in their 
exhibitions and competitions. 










The Personal Robot Developers (individuals, clubs, classes. . . 
whoever has a robot worth seeing) will exhibit their creations for 
a modest fee at the Robot Shops. Their operators can maintain, 
repair and modify their systems in these shops in view and within 
speaking distance of interested exhibit attendees. The PRDs will 
engage in a series of competitions. Awards will be given in the 
areas of "most useful," "most entertaining" and "open." The cate- 
gories of competition will be junior/senior high school, college, 
and general. Competition will culminate with the "Golden Droid" 
awards to be presented at the Sunday Brunch. 


Each registration includes admission to: 

• opening ceremony 

• technical sessions 

• commercial exhibits 

• Robot Shops and competitions 

• featured speeches 

• Awards Brunch 

Before Feb. 15: $125.00* (U.S. Dollars) 

After Feb. 15: $145.00* (U.S. Dollars) 



Passport #: 

(if not a U.S. Resident) 

Company Name: 

(if applicable) 


(or P.O. Box No.) 

City: State: 

Country: Zip: 

Area Code: Phone: 

No. of Registrations: 

Amount Enclosed: 

For correspondence and remittance, mail to: 

International Personal Robot Congress 
1547 South Owens Street, #46 
Lakewood, Colorado 80226 U.S. A. 





is a Robot 


In the beginning there were industrial robots de- 
signed to displace people in subhuman factory jobs. 
Twenty-five years after conception, the industrial robot 
has a foothold in every industralized society worldwide. 

Meanwhile, in an unrelated phenomenon, electronic 
arcade games became a frenzied fad, to be followed 
by mass-produced living room versions, that in turn 
spawned the home computer. 

Providing binding energy were the highly entertain- 
ing science fiction movies that celebrated superior 
robotic beings like R2D2 and C3PO. Even the sales 
promotion robots that roll around under hidden human 
control helped. 

Now, what can one really do with a home computer 
after one has balanced his checkbook and played Pac- 
Man with the kids? Not much, but suppose we add a 
peripheral that can provide a new kind of fun? Enter 
the personal robot! 

This year hosts the 13th International Symposium 
on Industrial Robots and the 1st Congress on Personal 
Robots. The former is a sophisticated full-blown event 
while the latter is bubbling over with naive awkward 
fervor. Industrial robots and personal robots are poles 
apart today. Giant corporations flex their muscles in 
the industrial arena while hobbyists are developing an 
underground culture in personal robotics. Yet, this 
schism cannot continue. 

Industrial robots are gaining sensory perception, ad- 
vanced language and mobility. And so are the hobby 
robots. With so many bright enthusiasts in the game 
the two robotics cultures must converge. Before this 
decade is out it should become evident that robots no 
longer need the distinctions industrial and personal. 
They will all be just robots “under the skin.” 

4 ROBOTICS AGE April 1984 

Circle 9 



June 4-7, 1984 

Cobo Hall • Detroit, Michigan 

See more than 200 robots in 
action at the largest robots 
show and conference ever! 
Whatever your industry, you'll 
find new robotic applications for 
assembly, finishing, painting, 
welding, machine loading, 
material handling, quality 

control, and more! At the 
conference, you'll meet 
international experts and learn 
about the latest advances in 
applications, systems, safety, 
human factors, theory, 
research, and education. Come 
see for yourself how ROBOTS 
8, the world's premier robotics 
event, will improve your 
company's productivity, product 
quality, and profitability. 


Exposition sponsored 
by Robot Institute 
of America D 


Conference sponsored by 
Robotics International ■ 
of the Society of 
Manufacturing Engineers 

Circle 20 



Call for papers. The Workshop on Non- 
monotonic Reasoning is sponsored by the 
American Association for Artificial Intelligence. 
The workshop aims to assemble theoreticians 
and practitioners from across the A I field who 
recognize a need for nonmonotonic reasoning. 
The objective is to identify those forms of plausi- 
ble reasoning which arise in different areas of 
AI, to isolate common patterns, to entertain 
various accounts of these reasoning patterns, 
and to evaluate their suitability and limitations. 
For more information regarding manuscript 
submission, due by 1 April, contact: Ray Reiter, 
General Chairman, Department of Computer 
Science, University of British Columbia, Van- 
couver, BC V6T 1W5, CANADA. 

Call for papers. The National Conference on 
Artificial Intelligence, AAAI-84, is the fourth 
national conference sponsored by the American 
Association for Artificial Intelligence. It will be 
held in Austin, TX on 6-10 August 1984. The 
purpose is to promote scientific research of the 
highest caliber in AI by bringing together 

researchers in the field and by providing a 
published record of the conference. Authors are 
invited to submit papers on: AI and Education, 
AI Architectures and Languages, Automated 
Reasoning, Cognitive Modeling, Expert 
Systems, Knowledge Representation, Learning, 
Methodology, Natural Language, Perception, 
Philosophical and Scientific Foundations, and 
Robotics. For more information regarding 
manuscript submission, due by 2 April, contact: 
American Association for Artificial Intelligence, 
445 Burgess Drive, Menlo Park, CA 94025, 
telephone (415) 328-3123. 

April. Robot Olympics. California State College, 
San Bernardino, CA. Contact: Robot Olympics 
Committee, Computer Center, California State 
College, 5500 State College Parkway, San Ber- 
nardino, CA 92407. The first Robot Olympics 
will be held on a weekend in April. Sponsored 
by various robot manufacturers, software 
developers, publishers, and dealers, the 
weekend will also sponsor introductory and ap- 
plication workshops. Competitions are design- 
ed for school grades kindergarten through 12. 

5-6 April. Computers and Young Children. 
University of Delaware, Newark, Delaware. Con- 
tact: Computers and Young Children Con- 
ference, Division of Continuing Education, 
University of Delaware, Newark, DE 19716. The 
program is designed for teachers, administra- 
tors, and researchers in preschool and early 
childhood education. Hands-on workshops and 
speakers from the Children's Television 
Workshop and Apple Education Foundation are 
featured. An open-to-the-public Computer Show 
follows the conference. 

13-15 April. International Personal Robot Con- 
gress & Exposition 1984. Albuquerque, NM. 
Contact: International Personal Robot Con- 
gress, 1547 S. Owens St., #46, Lakewood, Col- 
orado 80226, telephone (303) 278-0662. The 
Congress offers displays, exhibits, seminars, a 
number of cultural events portraying the history 
and mythology of personal robots, and an op- 
portunity for robot enthusiasts to display their 
creations and enter them in various robot com- 
petitions. A steering committee has been form- 
ed with representatives from Heath, RB Robot, 
and Androbot. Nels Winkless, robotics writer, 


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4 . STEPPER MOTOR 201 SM $16 

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12V, 21.5 OZ, 1.8° STEP SIZE 

6 . MOTOR MOUNT FOR 301 SM $25 
7 MOTOR MOUNT FOR 501 AM $ 12 
8 . MOTOR MOUNT FOR 501 AM $ 13 


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BOX 651, SMITHTOWN, L.I., N.Y. 11787 

TERMS Check. Money Order, C O D VISA or MasterCard 
Purchase Orders from Accredited Institutions 

6 ROBOTICS AGE April 1984 

Circle 1 

With Our Voice Recognition System 
All Robots Can Talk To One Another 


► VOREC— CMOS Microprocessor (65C02) based speech recogni- 
tion board mounts next to and interfaces with the HERO 

* Speaker-dependent with nearly instantaneous word 
recognition rates. 

* Recognition accuracy about 98%. 

* Operates without need for microphone. 

* 256 word vocabulary. 

* 16K onboard battery backed static RAM. 

► VOCOL— High level language firmware in EPROMS for the HERO 

* Supports Immediate and Deferred execution of voice 

* Automatic command training session handled by robot. 
► VOCOL Source Code: $55.00 extra (not sold separately.) 


9104 Red Branch Rd. 
Columbia, MD 21045 

(301) 730-1237 

Call or write for information 
about this and other products. 

MasterCard/Visa/Check/Money Order 
Add $3.00 for shipping 
Allow 3 weeks for delivery 

Circle 12 



SUMMER 1979: Digital Speed Control of DC 
Motors; Industrial Robots 79; Introduction to Robot 
Vision; The Grivet Chess-Playing Arm. 


WINTER 1979: Advances in Switched-Mode 
Power Conversion, Part 1; Prospects for Robots in 
Space; Robotics Research in Japan, Report from 

SPRING 1980: Microcomputer Based Path Con- 
trol; Robotics Research in France; Multiple Sensors 
for a Low-Cost Robot; the Robots of Autofact II; In- 
side Big Trak. 

SUMMER 1980: Industrial Robots; Today and To- 
morrow; Introducing the Minimover 5; Advances in 
Switched Mode Power, Part II. 

FALL 1980: Using Optical Shaft Encoders; Inter- 
view with Victor Scheinman; Robot Vision for In- 
dustry; The Autovision System; Industrial Robotics 
’80; Robots on Your Own Time; Superkim Meets 

JAN/FEB 1981: A Robot Arm Without a Budget; 
An Interview with Joseph Engelberger; Robots V— 
Dearborn 1980; Robots on Your Own Time; Opto 
‘Whiskers,” Robot Toy Designs. 

MAR/APR 1981: Video Signal Input; Chain-Code; 
Camera Geometry for Robot Vision; TIG Welding 
with Robots; Robot Digestive Track— Robots on Your 
Own Time. 

MAY/JUNE 1981: Rehabilitative Robots; A 
Homebuilt Computer Controlled Lathe; An Interview 
with Charlie Rosen; Superkim Meets ET-2, Part II. 

JULY/AUG 1981: Segmenting Binary Images; The 
Robot as Transfer Device; Continuous Path Control 
of Stepper Motors; TIM EL: A Homebuilt Robot. 

SEP/OCT 1981: Bullish Days in the Robot 
Business: Edge Detection in Man & Machine; Con- 
tinuous Path Control with Stepping Motors; Build a 
Low-Cost Image Digitizer, Report from JACC-81; The 
Robot Builder’s Bookshelf. 

NOV/DEC 1981 : Teach Your Robot to Speak; Fast 
Trig Functions for Robot Control; An Interview with 
George Devol; The Great Japanese Robot Show; 
TIMEL: A Homebuilt Robot, Part II. 

JAN/FEB 1982: Avatar: A Homebuilt Robot; A 
Look at SS-50 Computer Boards; Working Within 
Limits; Ambulatron: Another Contest Winner; 

MAR/APR 1 982: The Rhino XR-1 : A Hands-On In- 
troduction to Robotics; Power for Robots; A Com- 
puter Controlled Sentry Robot: A Homebuilt Project 
Report; Natural Language Understanding: A First 
Look; RT-13 Video/Sound Recognition System; An 
Inexpensive Hand; Type ’N Talk. 

MAY/JUNE 1982: Part Sources for Robots; An In- 
expensive Arm-Hand System; The Polaroid P100 
Polapulse Battery: Solution Waiting for a Problem; 
New Robot Books for the Bookcase: Applying Robot 
Vision to the Real World; Robots VI: A Landmark 
in an Exciting Era; Photo Essay and Notes from 
Robot VI. 

JULY/AUG 1982: The Microbot Teach-mover; 
Some Notes On the Rhino XR-1 and Minimover 5; 
Patent Probe; Use Your Apple As a Robotics 
Development System; IBM Robots; Adapting a 
Speech Synthesizer; Constructing an Intelligent 
Mobile Platform, Part I. 

SEPT/OCT 1982: Roving Robots; Report on SIG- 
GRAPH '82; Patent Probe No. 4,221,997; Construc- 
ting an Intelligent Mobile Platform, Part II; The 
Physics of One-Legged Mobile Robots. 

NOV/DEC 1982: Robot Wrist Actuators; Patent 
Probe; A Microcomputer Based, Real-Time Robot 
System; The Physics of One-Legged Mobile Robots; 
Part II; 1982 AAAI Conference; Armatron: A Study 
in Arm Engineering; Invention Documentation: A 

JAN/FEB 1983: The Move-Master RM 101; 
Mailmobiles in the Office; Teaching the Rhino XR-1 
to Write; The Philosophy and Birth of Computer 
Science; The 2-Roll Gripper. 

MAR/APR 1983: Nuclear Power Plant Emergen- 
cy Damage Control Robot; Artificial Intelligence and 
the Nature of Robotics; Patent Probe: Driverless 
Vehicle Autoguide; Lamberton Robots. 

MAY/JUNE 1983: Patent Probe: Multi-Purpose 
Mechanical Hand; XY Interpolation Algorithms; 
Designing With Optical Shaft Encoders; A Table of 
Contemporary Manipulator Devices; An Algorithmic 
Approach to Intelligent Robot Mobility. 

JULY/AUG 1983: The Get Away Special, Part I; A 
Nose for the Heath Hero-1; Patent Probe: Am- 

bulatory Platform; Robotics and the Law: Organiz- 
ing the Venture; A Table of Contemporary Manipu- 
lator Devices. 

SEPT/OCT 1983: ODEX 1: The First Functionoid; 
A Cog-Wheel Driven Robot Cart; A Table of Con- 
temporary Manipulator Devices; Patent Probe: A 
Portable Robot Task Analyzer; The Penpad: Hand- 
written Input for Computers; The Get Away Special, 
Part II: Flight Preparations. 

NOV/DEC 1983: Complete Control with Forth on 
a Chip; A Simple Sense of Touch for Robotic Fingers; 
Current Offerings in Robotics Education; Single 
Board Computer Manufacturers; A Table of Contem- 
porary Manipulator Devices; Welding Apparatus 
with Vision Correction. 

JANUARY 1984: Robots in Batch Manufacturing; 
Super Armatron; Directory of Robotics Education 
and Training Institutions; A Table of Contemporary 
Manipulator Devices; Patent Probe: A New Robot 
Patent Category; Operator Roles in Robotics; The 
Scorpion: Software Overview. 

FEBRUARY 1 984: GRASP: From Computer Aided 
Robot Design to Off-Line Programming; Design and 
Construction of a Five-Fingered Robotic Hand; Pat- 
ent Probe: Omnidirectional Vehicle; Using Micro- 
processors with Radio-Control Servos; Designing 
a Reliable Voice-Input Robot Control Language; Part 

II, The Scorpion: Motor Control Instructions. 

MARCH 1984: Part I, Armega 33: Mechanical 
Design; Patent Probe: Robot Computer Chess; Part 

III, The Scorpion: Commands with Responses; A 
Simple Computer Interface. 


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and Russ Eberhart, robot retailer, are also on 
the committee. 

Conference events include robot competi- 
tions, instructional sessions, and speakers such 
as Joseph F. Engleberger, David L. Heiserman, 
Nolan Bushnell, and Isaac Asimov. The various 
instructional sessions include hardware and 
software design considerations; legal issues; 
human services; robots in education; business 
opportunities; and the future of personal robots. 

23-26 April. Robotics and Remote Handling 
in Hostile Environments. Sheraton Hotel, 
Gatlinburg, TN. Contact: Norbert R. Grant at 
(615) 574-7123 or Howard W. Harvey at (615) 
483-0228, or write to Technical Program Chair- 
man, PO Box 326, Oak Ridge, TN 37830. The 
meeting is sponsored by the American Nuclear 
Society's Remote Systems Technology Division 
(ANS/RSTD) and the Oak Ridge/Knoxville ANS 
Section. Session titles are: History of Manipu- 
lators and Robotics; Sensory Systems; Control 
Technology; Manipulator and Robot Applica- 
tions; Remote Systems Applications in the 
Nuclear Industry— Fission; Remote System Ap- 
plications in Other Hostile Environments; 

Technology Development and Remote Systems 
Technology Developments at ORNL. 

24-26 April. Robotics Conference. Huntsville, 
Alabama. Contact: Sue Charles, Conference 
Coordinator, Division of Continuing Education, 
University of Alabama in Huntsville, Huntsville, 
AL 35899, telephone (205) 895-6015. This 
three-day conference includes a one-day tutorial 
on robotics and its applications, with hands-on 
training, and two days of presentations on in- 
dustrial robots in manufacturing, welding, and 
hazardous environments as well as new trends 
in vision, sensing, expert systems, and future 

24-25 April. 1984 Conference on Intelligent 
Systems and Machines. Oakland University, 
Rochester, MI. Contact: Professor Nan K. Loh 
or Donald R. Falkenburg, Center for Robotics 
and Advanced Automation, School of Engineer- 
ing and Computer Science, Oakland Universi- 
ty, Rochester, MI 48063. The conference will 
be hosted by the Center for Robotics and Ad- 
vanced Automation in cooperation with spon- 
soring government agencies and private in- 

dustry. The conference’s aim is to foster com- 
munication among engineers, scientists, govern- 
ment officials, and military services regarding 
issues, trends, and needs in research and 
development. Areas covered include artificial 
intelligence, hardware systems, software systems, 
and applications. 


7-11 May. 1984 Computer-Aided Engineering 
and Manufacturing Seminars and Exhibition. 
North Carolina State University, McKimmon 
Center, Raleigh, NC 27605. Contact: Alice 
Strickland, NCSU, Division of Continuing 
Education, Box 5125, Raleigh, NC 27650, 
telephone (919) 737-2261. 

7-11 May. Microcomputers in Control Systems 
Including Interfacing Methods. Course 
#5220C. Ottowa, Canada. Contact: George Har- 
rison, The George Washington University, Divi- 
sion of Continuing Education, Washington, DC 
20052, telephone (800) 424-9773 or (202) 
676-6106. This course is designed to familiarize 


The Curriculu m 

The curriculum includes 7 instructional modules 
which begin with the basics and conclude with 
advanced applications. 


• Detailed Instructor’s Manual 

• 7 Student Texts 

• Hands-on Workbook Exercises/Experiments 

• Videotape 

• Transparencies 

• Supplemental AV Presentations 

The Hardw are 

The SCORBOT Robot is the focal point of a total 
hardware package which includes: 

• The Robot with D.C. Servo Gear Motor Drive and 
5 Axes of freedom plus Gripper 

• The 8 Axes Controller with 8 lnputs/8 Outputs 
and an RS-232C Interface 

• The Microcomputer — software compatible for 
Apple, IBM and TRS-80 personal computer 

• Other hardware such as a Teach Pendant, Vision 
Systems and Conveyor Belt, among others are 
currently under development 

For a free detailed proposal, call PREP, Inc. toll free 
800-257-5234 or 609-882-2668. Or write to: PREP, 
Inc., 1007 Whitehead Road Ext., Trenton, NJ 08638 

PREP, Inc. is the exclusive distributor in the United 
States and Canada for ESHED, Robotec, Ltd., Israel. 

Circle 17 

ROBOTICS AGE April 1984 9 

Read About It First 


Don't Miss A Single 
Monthly Issue 

We’ve read about robots for decades in 
the science fiction genre. Today’s creative 
engineers are fast making yesterday’s fic- 
tion obsolete. The technology is becoming 
real . . . Real engineering of real-time com- 
puter systems for real applications — that’s 
what robotics is all about. Robotics Age is 
your monthly window on the nuts, bolts, 
bits and design concepts of this new 
microprocessor hardware and software 
technology. The inspiration of science fic- 
tion plus the practical information in 
Robotics Age keep you abreast of this ex- 
citing field. 

Intelligent machines are already a major 
part of our world. We see the new realities 
of walking machines, autonomous space 
and undersea explorers, factory automa- 
tion, feedback from vision and touch, 
robots of the industrial and personal 
flavor. We see sentry robots patrolling 
homes, forts, factories and offices. We see 
the prospect of the automotive autopilot 
and personal robotics. 

Robotics Age looks to this future with 
articles about design concepts, products 
and practical experimental techniques. 
You’ll find advertising from the suppliers 
of components and systems for intelligent 
machine engineering, as well as in-depth 
tutorials and reviews of available technolo- 
gies. You’ll find numerous practical and 
proven design techniques. You’ll learn 
how to use microcomputer electronics 
where it counts, how to build simple, 
reliable touch sensors, how to use visual 
and aural pattern recognition to gain in- 
formation about the real world, how to 
design programs that plan strategies of 
operation. You’ll find articles on what 
makes today’s personal robotics ex- 
periments tick, and more 

Robotics Age Has the 
Information You Need- 
First and In Detail 

In past issues, we’ve had several articles 
on walking robots — the design problems 
of legged mobility. One article described 
aspects of a one-legged hopping robot. 
Another described ODEX I, a recently 
designed experimental six-legged mobile 
robot. ODEX I has been widely publi- 
cized, including an appearance on a 
syndicated television series as well as 

superficial articles in numerous general 
magazines. If you were a subscriber in 
1983, you read about ODEX I first. In ad- 
dition to being first, our article on ODEX 
I contained a level of detail only available 
in the Robotics Age style of technical ar- 
ticle . . . and nowhere else. So, don’t miss 
out on the opportunity to find out about 
the latest developments in detail and 
ahead of the crowd — subscribe today. 

Your subscription to Robotics Age is 
the key to this technology. You get month- 
ly exposure to new and exciting informa- 
tion as it becomes available. 

Subscribe Today 

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participants with the capabilities of microcom- 
puters to replace digital, analog, and elec- 
tromechanical control elements in control ap- 
plications. Participants are shown the current 
state of technology in microcomputers and 
become familiar with both the economic and 
technical aspects of the use of such systems as 
replacements for more conventional control 
methods. This course is for technicians, engi- 
neers, and technical managers who are inter- 
ested in the applicability, selection, and use of 
microcomputers, and who want hands-on un- 
derstanding of applications and interfacing of 
microcomputers in control systems. 

22-24 May. Control Expo 84. O’Hare Exposi- 
tion Center, Rosemont, Illinois. Contact: Tower 
Conference Management Company, 331 W. 
Wesley St., Wheaton, IL 60187, telephone (312) 
668-8100. Control Expo is sponsored by Con- 
trol Engineering Magazine. Over 6,000 controls 
specialists are expected to attend this year’s ex- 
position. A comprehensive conference program 
of 25 technical sessions cover topics ranging 
from controlling flexible assembly systems, sen- 
sors for adaptive control systems, applications 

and advances of standalone digital process con- 
trollers, fitting robots to the applications, and 
advances in the control of large batch processes. 

IUNE _ _ 

4-7 June. Robots 8. Cobo Hall, Detroit, MI. 
Contact: Jeff Burnstein, Robotics Institute of 
America, PO Box 1366, Dearborn, MI 48121, 
telephone (313) 271-0778. The theme for this 
year’s annual Robots show is “Merging Tech- 
nologies.” More than 20,000 specialists, in- 
dustrialists, and manufacturing engineers, and 
executives are expected to attend the four-day 
event. The conference features more than 80 
leading experts explaining new aspects of robot 
implementation, applications, and research. 
The exposition will occupy the entire main level 
and additional exhibit space at Cobo Hall. 

19-21 June. 3rd Canadian CAD/CAM & 
Robotics Exposition and Conference. Toronto 
International Centre of Commerce. Contact: 
Hugh F. Macgregor & Associates, 662 Queen 
Street West, Toronto, Ontario M6J 1E5 

CANADA, telephone (416) 363-2201. This ex- 
position is the major Canadian marketplace for 
advanced manufacturing systems. Conference 
topics include: Robotics Justification for 
Management, CAD/CAM, Robotics Education, 
Robotics Socio-Economic Considerations, 
Robotics Engineering, and Robotics 


9-12 July. 1984 National Computer Conference. 
Las Vegas Convention Center, Las Vegas, NV. 
Contact: Ann-Marie Bartels, Las Vegas Conven- 
tion Center, Las Vegas, NV, telephone (703) 
558-3613. Enhancing Creativity is the theme 
of the twelfth annual NCC. The conference will 
focus on how the widespread availability of com- 
puting resources is altering the office, factory, 
and home. 

23-27 July. SIGGRAPH ‘84. Minneapolis, MN. 
Contact: SIGGRAPH Conference Office, 111 
East Wacker Drive, Chicago, IL 60601, 
telephone (312) 644-6610. 

Now Your Computer 
Can See! 

‘The MicronEye® camera is an ex- 
tremely versatile image-sensing device 
that can be used in many personal, scien- 
tific. or industrial applications. The unit’s 
cost makes it particularly attractive.” 
Chris Weiland 
BYTE” Oct. ’83 

“Plug it in. turn it on. and you have 
pictures on your screen.” 

Ben Dunnington 

“Strongly recommend the Micron- 
Eye to anyone working with computer 

Mike Rigsby 
“Color Computer" Nov. ‘83 

”... well engineered, superbly doc- 
umented. crawling with support soft- 

Steve Rimmer 
“Computing NOW!” Sept. '83 

The MicronEye is a complete plug- 
and-go vision system for your computer. 

This unique product includes all the 
software and hardware necessary to al- 
low your computer to see. 

Images can be stored in your com- 
puter's memory, enabling the computer 
to store, retrieve, print, analyze and ma- 
nipulate what it sees. 

The MicronEye has selectable reso- 
lution modes of 256 x 1 28 and 1 28 x 64 
with an operating speed of up to 15 im- 
ages per second in the lower resolution 

The MicronEye is designed around 
a revolutionary new micro-chip (created 
and manufactured by Micron Technolo- 
gy) that can see — the IS32 OpticRAM® 
image sensor. 

The OpticRAM automatically digi- 
tizes the image to 1 s and 0’s. Multiple 
scans of the same image using different 
exposure times allow the MicronEye to 
see shades of grey. 

The MicronEye can be used for 
graphics input, robotics, digitizing, text 
and pattern recognition, security, auto- 
mated process control, and much. much, 

Give your computer the ability to see 
with the MicronEye from Micron Tech- 
nology. Inc. 


MicronEye versions currently available for 
the Apple II + . Apple He. IBM PC. Commodore 
64. and the TRS-80 Color Computer. (RS-232 
version information available upon request.) 

Complete MicronEye system $295. Please in- 
clude $8.00 for shipping and handling (Federal Ex- 
press Standard Air). Sales tax required for 
residents of AK. A Z. CA. CO. CT. FL. GA. IA, 
II). IL. IN. LA. MA. MD. ME. Ml. MN. NC. NE. 
NJ. NY. OH. PA. SC. TN. TX. UT. VA. VT. 



2805 East Columbia Road 
Boise, Idaho 83706 
(208) 383-4106 
TWX 910-970-5973 

MicronEye “Bullet*' 

Apple. IBM PC. Commodore 64. and TRS 80 Color Computer are trademarks of Apple Computer Inc.. International Business Machines. Commodore Corporation and Iandy Corporation respectively. 

Circle 14 

ROBOTICS AGE April 1984 11 


This year’s SIGGRAPH Conference attendees 
will be treated to a vast array of technical and 
exhibit offerings. The program includes up to 
30 one or two-day courses, panels on topical 
computer graphics issues, a larger number of 
exhibits, a design arts show, and the premier 
of the first totally computer-generated Omnimax 


1-3 August. The Computer: Extension of the 
Human Mind. Eugene, Oregon. Contact: Sum- 
mer Conference Office, College of Education, 
University of Oregon, Eugene, Oregon 97403. 
This conference, the third annual computer and 
instructional technologies conference to be 
sponsored by the Center for Advanced Tech- 
nology in Education, will focus on the needs 
of the individual who has become responsible 
for school and district-level use of computers 
and other emerging instructional technologies. 
Both general and special interest group sessions 

will be supplemented with an extensive vendor 
hall and film/video theater related to com- 
puter technology in education. Pre- and post- 
conference workshops will be conducted on the 
educational uses of computers. 

5-8 August. Lisp and Functional Program- 
ming. University of Texas at Austin. Contact: 
Robert S. Boyer, University of Texas at Austin, 
Institute for Computing Science, 2100 Main 
Building, Austin, TX 78712, telephone (512) 
471-1901. This is the third in a series of biennial 
conferences on the Lisp language and issues 
related to applicative languages. Areas of in- 
terest include implementation problems; pro- 
gramming environments; large implementa- 
tions; support tools; architectures; microcode 
and hardware implementations; significant 
language extensions; lazy evaluation; functional 
programming; logic programming; combinators; 
FP; APL; Prolog; and other languages. 

20-24 August. National Conference and Ex- 
hibition on Robotics— 1984. Melbourne, 

Australia. Contact: The Conference Manager, 
Institution of Engineers-Australia, 11 National 
Circuit, BARTON, A.C.T. 2600, AUSTRALIA, 
telephone (062) 73-633. The conference prom- 
ises to be the most important Australian robotic 
event held to date. It will have a strong applica- 
tion and education emphasis. Leading Austral- 
ian robot users, developers, and researchers will 
present their experience and views on this im- 
portant high technology area. 


27-29 November. Robots-West. Anaheim Con- 
vention Center, Anaheim, CA. Contact: Jeff 
Bumstein, Robot Institute of America, PO Box 
1366, Dearborn, MI 48121, telephone (313) 
271-0778. Robots-West is RIAs first regional 
show. It will feature exhibits by leading robot 
manufacturers and component suppliers. Ap- 
proximately 6,000 visitors are expected to at- 
tend the three-day exposition and conference. 


Keyboard or Joystick Control 

Remembers Everything It Did 
& does it again 

Typical System Includes: 

. Robot-1 & Cables 
. 6 Channel Servo Controller 
. Power Supply 

. All Software with source code 

Modular Robotic Accessories: 

. Mobile Cart for Traveling 

. Radio Links between all 

. Robot-mounted MIcronEye 
. Ultrasonic Range Finder 

Robot- 1C for Color Computers- $395.00 
Robot- 1$ for SS50 Systems -$395.00 
Robot MicronEye- $295.00 

Additional Systems Available 
Robot- 1G for General Purpose Computers 
Robot- 1R for Radio Control Systems 

Computer Servo Controlled Robot Arm 

for Free Catalog 

Analog micro Systems 

5660 Valmont Road . Boulder, Colorado 80301 .Tel: (303)444-6809 

1 2 ROBOTICS AGE April 1984 

Circle 2 


Startup Aid 

Thank you for including the RMP 2000 in 
the Sept/Oct 1983 New Products column. Your 
magazine provides a valuable service by 
devoting several pages each issue to new robot- 
related products. This service is valuable not 
only to Robotics Age readers, but also to 
established companies and start-ups such as 
Bingel Robotics. 

Thank you again, 
Tom Bingel, President 
Bingel Robotics Company 
3540-244 SW Archer Rd. 
Gainesville, FL 32608 

GAS Handbook 

Could you please provide the address 
necessary to obtain the GAS User’s Handbook 
and related information? 

Mr. S. Pacitti 
120 Homewood Ave. 

North York, Ontario M2M 1K3 

The Get Away Special (GAS) Handbook 
describing how to design experiments for 
transportation on special Space Shuttle laun- 
ches can be obtained from: The Get Away 
Special Program , Technical Liaison Office/Code 
741 , Goddard Space Flight Center, Greenbelt, 
MD 20770. 

DCAM Sources 

We appreciate your covering the Micro DCam 
in your last issue of Robotics Age, but we would 
like to clarify some of the wording in the in- 
terest of our suppliers. 

Micromint manufactures the camera circuitry 
and interface electronics of the Micro DCam, 
but the 256 by 128 silicon image sensor itself 
is manufactured by Micron Technology in Boise, 
Idaho. The editing of our new products an- 
nouncement makes it seem we are the image 
sensor manufacturer. 

We would not bother to bring this to your 
attention except that your magazine does such 
a great job it produced a flood of inquiries con- 
cerning the Micro DCam. We’re not 

Joyce Chandler 
Micromint, Inc. 
223 Merrow Rd 
Tolland, CT 06084 

Armatron Recognized 

You had an article on Radio Shack’s Ar- 
matron in your Nov/Dec 1982 issue [also the 
January 1984 issue, ed]. Would this robot arm 
be a good one to buy? Were there any tests con- 
ducted between this robot and any other robot 

Very truly yours, 
Bruce Cook 
127 Oak Glen Dr. 

San Antonio, TX 78209 

Although the Radio Shack Armatron is an 
intriguing mechanical device, it is not a true 
robot. Our coverage of the machine has 
stressed the Armatroris educational value. If 
you wish to discover the intricacies of 
mechanical gearing, controls, and linkages, the 
Armatron is definitely a good value. At $35, 
how can you go wrong? However, don't expect 
to connect the Armatron to your computer as 
soon as you get it home. Computer control re- 
quires major modifications. 

EX Roll Home 

I wish to comment about a recent Patent 
Probe which appeared in the February, 
1984 issue and described Hua T. La's 
"Omnidirectional Vehicle." I am par- 
ticularly interested in figure 1, "a front 
elevational view of a wheel defined by the 
La patent . . . 4,237,990 Hua T. La; Decem- 
ber 1980 . . 

It appears that several legal precedents 
might have been established by the is- 
suance of this patent. 

I'm familiar with at least three written 
accounts of this wheel configuration be- 
ginning with that given by a man named 
Ezekiel around 593 BC. Ezekiel was 
studying to become a priest as had his 
father Buzi before him. About 597 BC he 
was deported to Babylon with other Jews 
by King Nebuchadnezzar after the sur- 
render of Jerusalem to the Babylonian Ar- 
mies by King Jehoiachin. Soon after his 
30th birthday he was called into service 
as a prophet. He kept meticulously de- 



Commercial Uses of Artificial Intelligence 

edited by Patrick H. Winston and Karen A. Prendergast 

Is Artificial Intelligence a new frontier with great possibilities and 
unlimited investment potential? Or is it simply hype? How are 
smart machines being used today? 

In this important new book, industry professionals, researchers, 
and financial analysts discuss real-world applications of AI tech- 
nology-in the computer industry, medicine, the oil industry, and 
electronic design -and show how AI can be a way out of our 
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come from and where they are going to come from, the pros and 
cons of investment opportunities, the Japanese threat, and what 
our colleges and universities should be doing with computers. 

28 Carleton Street 

Cambridge, MA 02142 


Circle 15 

ROBOTICS AGE April 1984 13 


tailed and orderly records of the things 
that he saw. 

The Book of Ezekiel is full of "visions" 
of wheeled vehicles. Chapter 1, verses 16 
and 17 make the first actual mention of 

T he appearance of the wheel and their 
work was like unto the color of beryl: 
and the four had one likeness: and their 
work was as it were a wheel in the mid- 
dle of a wheel 

‘When they went they went up on 
their four sides: and they turned not 
when they went — 
i( ...and when the living creatures 
went the wheels went by them ” 

Unfortunately, the language of the day was 
such that it could not identify the craft, leav- 
ing we of Ezekiel’s future with descriptions of 
“animals” that moved about upon wheels. 

He continues recording his impressions of the 
things that he witnesses and then again in 

chapter 10 verse 11 he makes mention of the 

“As I was looking at the four animals 
I saw four wheels touching the ground 
...all four wheels were alike . . . each 
had another wheel intersecting it at right 
angles — ” 

Most notable, however, are his descriptions 
of how they operated: 

“When the animals moved they could 
go in any direction without turning. 
They all moved in the direction they 
wanted to go without having to turn 
round ” 

This is most clearly a functional description 
of the omnidirectional wheel patented by Mr. 
La. Without a doubt, Ezekiel saw vehicles that 
came from the air, landed, and then moved 
about upon wheels capable of omnidirectional 
movement without the need to rotate the en- 
tire craft. Unfortunately, this information lay un- 
noticed for centuries. 


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• FORTH allows full access to DOS 
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• FORTH application programs can 
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and distributed with no license fee. 

• FORTH Cross Compilers are 
available for ROM’ed or disk based ap- 
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FORTH Application Development Systems 

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Z-80 FORTH for CP/M® 2.2 or MP/M II, $50.00; 
8080 FORTH for CP/M 2.2 or MP/M II, $50.00; 
8086 FORTH for CP/M-86 or MS-DOS, $100.00; 
PC/FORTH for PC-DOS, CP/M-86, or CCPM, 
$100.00; 68000 FORTH for CP/M-68K, $250.00. 

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Phone credit card orders to (213) 306-7412 

Then, for whatever reasons, the late 1970’s 
witnessed an upsurge in public interest and 
speculation in space flight. During this time 
many people did research into the possibility 
that Planet Earth had been visited by extrater- 
restrials and that they’d left a wealth of 
knowledge, right under our undisceming noses. 
These researchers published their findings for 
all to read and wonder about. One of the most 
prolific of the researcher/writers was one Erich 
von Daniken, author of Chariots of the Gods. 

Mr. von Daniken made mention of many of 
these curious descriptions written in the Ezekiel 
texts because he felt that they could be descrip- 
tions of spacecraft. Few, however, regarded his 
work as being of real scientific value. 

Independent work by Josef F. Blumrich, 
author of The Spaceships of Ezekiel, later sup- 
ported much of Mr. von Daniken’s research. Mr. 
Blumrich’s book provides an appendix complete 
with formulae for spacecraft and fuel, all of 
which were derived from descriptions left 
behind by Ezekiel. 

My questions, however, are centered around 
the similarity between the wheel illustrated on 
page 38 of Mr. Blumrich’s text and that used 
to describe Mr. La’s patent application on page 
21 of the February 1984 issue of Robotics Age. 

Assuming that these UFOs did (do) exist, isn’t 
it reasonable to believe that the occasional 
sightings are actually return visits being made 
to reapply for patent law protection? 

Can an invention whose patent rights were 
established by extraterrestrials be patented by 
a Terrestrian? 

If not, and the existence of UFOs is ever ac- 
knowledged and occupants of said UFOs decide 
to sue for infringement of patent rights— in 
whose favor might the courts rule? 

How did a patent attorney ascertain the 
presence or lack of “novelty” as defined in 35 
US Code 101 when dealing with devices which 
may or may not have been first introduced by 
an extraterrestrial? 

I enjoy your magazine tremendously and am 
hoping that through your publication and its 
efforts to educate the public, America’s work 
in the area of robotics will not lag behind that 
of the Japanese or the ETs. 

Gregory W. Jones, Jr. 

Lake Hiawatha, NJ 

We have published this letter in the public 
interest , to provide new legal insights into the 
potential problems of intergalactic patent ap- 
plications. Although no staff member has yet 
completed galactic legal training, lam sure Mr. 
Jones' questions will be brought up at the next 
pangalactic jamboree frgacj. 

1 4 ROBOTICS AGE April 1984 

Circle 10 

Closing the Sensor- 
Control Loop 

R. Andrew Russell, Ph.D. 

Department of Electrical and Computer Engineering 
The University of Wollongong 
PO Box 1144 

Wollongong, N,SW. 2500 AUSTRALIA 

I was looking for a simple demonstra- 
tion of robot control for our department’s 
open day. To hand, I had a newly acquired 
Mitsubishi Movemaster robot and a Cro- 
memco microcomputer. The Movemaster 
is a solidly built, five degrees of freedom 
experimental robot arm. 

Its step motor drives are 
controlled by an inbuilt 
Z-80 microprocessor. 

“What demonstration 
could I put together,” I 
asked myself, “which 
would illustrate the ad- 
vantages of using sensory 
feedback to guide a 
robot?” My demonstra- 
tion had to conform to 
the usual constraints of 
costing very little and not 
involving too many man- 
hours of work. 

I reasoned that part ac- 
quisition is a useful task, 
so why not show the 
robot locating and stack- 
ing randomly placed ob- 
jects? I wrote a check list of additional 
items this demonstration would require: 

• A sensor for finding the objects. 

• Some method of sending the robot 
manipulator to a specified point in the 
search area (a way of converting a 
specified point in Cartesian xyz coor- 
dinates into robot joint coordinates). 

• A strategy for finding and accurately 
locating the objects. 

This article describes my implementa- 
tion of each of these items which have been 
combined to make a very successful 
robotics demonstration. The methods I 

have used should be useful in many other 

The Sensor. Vision is the natural first 
choice of a sensor for locating randomly 
positioned objects. However, this solution 
was ruled out on grounds of cost. 
Whisker sensors are quite common in 

nature. Many insects and nocturnal 
animals use antennae and whiskers to 
check for obstacles and gauge clearances 
in tight situations. (Shiva the cat shows her 
whisker sensors in photo 1.) 

My whisker sensors consist of a length 
of metal guitar string, 
0.007 in. diameter, which 
passes through a hole in 
a piece of copper sheet. 
The smaller the hole, the 
more sensitive the sensor. 
There is a lower limit to 
the size of hole set by the 
difficulty of positioning 
the wire centrally in the 
hole and by vibration 
causing spurious re- 
sponses. When the wire 
whisker is deflected by 
contact, the wire touches 
the side of the hole. This 
completes a circuit and 
changes the logic level on 
a computer input line. 

The first sensor I built 
consisted of an array of 
16 whiskers having different lengths and 
heights. This sensor, shown in figure la, 
was intended to give some two-dimensional 
information about the height and outline 
of objects that it touched. To reduce the 
number of computer interface lines re- 
quired by this sensor, I designed the scan- 
ning circuit shown in figure 2. This circuit 

ROBOTICS AGE April 1984 1 5 

Figure 1. The original whisker sensor, shown in figure la, was constructed from 16 guitar wires passed through 
a copper sheet Once this was completed, I discovered that the sensor was too large to be placed on the 
robot hand. The second version, figure lb, used a single wire for sensing the presence of an object. 



+ 5V 



22/aF 8 








r 1 

















OUT ^ — r 

















I 3 















! ^ 

< 100K 





Figure 2. The 16-whisker array sensor interface. This circuit requires only two output lines and one input 
line to read 16 whisker sensors. 

1 6 ROBOTICS AGE April 1984 

requires two output lines and one input 
line to read 16 whisker sensors. When the 
LOAD line is pulsed, the 4014 shift regis- 
ers are parallel loaded with the present 
state of each whisker. Successive pulses on 
the SHIFT line clock data out of the shift 
registers so that it can be read into the 
computer from the DATA OUT line. This 
sensor performed quite well at detecting 
the outlines of differently shaped blocks. 
Some results are shown in photos 2, 3, and 
4. However, when I came to mount this 
sensor on the robot gripper, I found that 
it was too large. A redesign was called for 
and the result was a much more compact 
single whisker sensor. 

Details of this sensor are shown in figure 
lb. This simplified design can only detect 
the presence of an object, not its shape or 
orientation. For this reason, I chose to 
search for cylindrical objects so that when 
they are standing on end, they can be 
grasped without worrying about their angle 
of rotation. If the objects had been square 
blocks, their angle of rotation would be re- 
quired so that the manipulator could be 
oriented to grasp across parallel faces of 
the block. 

Joint Angle Calculation. In the following 
description, when I write “joint angle” I am 
referring to the number of step motor 
pulses to move the robot arm from its nest 
position to a particular joint angle. 

In order to program the locate and grasp 
operations I needed some way of sending 
the robot arm to particular points in the 
search area. If these points are known in 
advance, I could program the computer 
with robot joint angles for each point. Un- 
fortunately, some of the points are not 
known in advance. The usual method used 
to convert from search area coordinates to 
robot joint angles is to use matrix transfor- 
mations. This method is complicated and 
requires trigonometric functions. Although 
the programs for this demonstration were 
originally written in BASIC, I intended to 
translate them into assembler. Therefore, 
I wanted to avoid trigonometric functions 
if at all possible. 

Following on from a previous interest in 
methods of interpolation, I decided to 
apply linear interpolation to the problem. 
The method involves storing joint angles 
for a few points and interpolating between 
them to find the joint angles correspond- 
ing to intermediate points. To illustrate the 
method, assume the robot arm can only 

move in one direction, that is, along the 
x-axis. Five joint angles must be considered 
for a five-degree-of-freedom arm, but the 
method is essentially the same for each 
joint angle. 

Figure 3. A graphic example of two-dimensional in- 
terpolation. The Cartesian coordinates of a particular 
point can be found by estimating the differences be- 
tween two adjacent points for which position values 
are known. 

Consider a joint angle theta, 0, which 
can be any one of the robot joint angles. 
Referring to figure 3, the joint angles are 
known for two values of x (x a and x b ). To 
find the joint angle for an intermediate 
position, x p , we use a formula which 
assumes that the function relating x to 0 
is a straight line: 

0p (tr r ii) (Xp Xa) + 0a 

The value found by interpolation will dif- 
fer from the true value. Providing the 
known points are not spaced too far apart, 
the accuracy will be adequate. In our case, 
the error could be neglected when inter- 
polating between points spaced 5 cm 
apart. This method was readily generalised 
to three dimensions by applying the one- 
dimensional method seven times. Referring 
to figure 4, a, b, c, d, e, f, g, and h are the 
points where 0 is known and point p is the 
position where we would like to know 0. 
We proceed as follows: 

1. Assume a plane perpendicular to 
the x-axis which passes through p and 
cuts the line joining a and b to i. Use 
linear interpolation to find 9 { and in a 
similar manner 0 jf 0 k , and 0j. 

2. A line through p in the z direction 
cuts the line joining k and 1 at m. Use 

Photo 2. The array whisker sensor detecting a square block. The detected bit pattern is: 





Photo 3. The array whisker sensor detecting an octagonal block. The detected bit pattern is: 





ROBOTICS AGE April 1984 17 

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990 REM *************************** 

1030 REM 

1050 RM 

1060 X1=INT(X) : Y1=INT(Y) : Z1=INT(Z) 

1080 X2=X1 +1 : Y2=Y1 +1 : Z2=Z1+1 

1090 RM 

1140 RM 

1150 IF X<0 THEN XI =0 : X2=1 
1160 IF X>=4 THEN XI =3 : X2=4 
1170 IF Y<0 THEN Y1=0 : Y2=1 
1180 IF Y>=2 THEN Y1 =1 : Y2=2 
1190 IF Z<0 THEN Z1=0 : Z2=1 
1200 IF Z>=2 THEN Z1=1. : Z2=2 
1210 RM 

1230 RM 

1240 X3=X-X1 : Y3=Y-Y1 : Z3=Z-Z1 
1250 RM 





1300 RM (X VALUE) +5* (Y VALUE)+15*(Z VALUE) 445* (JOINT NUMBER) 
1310 RM 

1320 FOR I = 0 TO 4 

1330 T(I) = (D(X2+5*Y2+15*Z2+45*I)*X3+D(X1+5*Y2+15*Z2+45*I)* 

1340 T(I) = T(I)+(D(X2+5*Y2+15*Z1+45*I)*X3+D(X1+5*Y2+15*Z1 + 
45*I)*(1-X3) )*(1-Z3) 

1350 T(I) = T(I)*Y3 

1360 T(I) = T(I)+(D(X2+5*Y1+15*Z2+45*I)*X3+D(X1+5*Y1+15*Z2+ 
45*1 ) * ( 1 -X3) ) *Z3* ( 1 -Y3 ) 

1370 T(I) = T(I)+(D(X2+5*Y1+15*Z1+45*I)*X3+D(X1+5*Y1+15*Z1+ 

1380 RM 

1410 RM 

1420 T(l)=INT(T(l) ) 

1430 NEXT I 
1440 RETURN 

18 ROBOTICS AGE April 1984 

Listing 1. The three-dimensional interpolation subprogram written in BASIC. 

linear interpolation to find 0 m and in a 
similar manner 0 n . 

3. Use linear interpolation between m 
and n to find 0 P . 

When equations for the seven stages of 
linear interpolation are combined, we have 
one equation which gives an estimate of 
0 P in terms of known joint angles and Ax, 
Ay, Az, the relative coordinates of p. This 
equation only involves addition, subtrac- 
tion, multiplication, and division. If we 
assume that the scale of our xyz coordinate 
system is such that the known points are 
unit distances apart, then the equation for 
0 P can be simplified to: 

0 P = ((0gAx + 0 h (l - Ax))Az + (0 c Ax + 
0 d (l - Ax))(l - Az))Ay + ((0 f Ax + 0 e (l 
- Ax))Az + (0 b Ax -l- 0 a (l - Ax))(l - 
Az))(l - Ay) 

Photo 4. The array whisker sensor detecting a triangular block. The detected bit pattern is: 





Figure 4. A graphic example of three-dimensional interpolation. By placing the known points in the xyz 
coordinate system unit distances apart, the formula for determining the point p can be written using only 
multiplication, addition, and subtraction. 

After simplification, the equation does 
not require division. A BASIC subroutine 
to perform this calculation is shown in 
listing 1. 

The subroutine uses stored joint angles 
for 45 points, five in the x direction, three 
in the y direction, and three in the z direc- 
tion. To position the robot arm at a par- 
ticular point, coordinates of the eight 
known points surrounding the unknown 
point are calculated. The three- 
dimensional interpolation equation is then 
used to calculate the five joint angles which 
will position the robot arm at the desired 
point p. 

So far there has been no mention of the 
orientation of the robot gripper, only its 
position. The method of linear interpola- 
tion outline here works for only one grip- 
per orientation. Each known point is re- 
corded with the gripper in that orientation. 
I chose a vertical orientation for easy lif- 
ting and stacking. At the moment, I am 
working on the generalisation of this 
method to a range of gripper orientations. 

Search Strategy. The whisker sensor can 
sweep through an area to detect objects 
if it can be maintained broadside-on to the 
direction of motion. Because the hunted 
object is stationary, the most efficient 
strategy to locate it is to perform a parallel 
grid pattern search. The search path is il- 
lustrated in figure 5. Search sweeps are 
performed in the y direction. After each 
sweep, the arm steps forward in the x direc- 
tion. Since the Movemaster robot cannot 
be stopped in the middle of a move be- 

ROBOTICS AGE April 1984 19 

tween two points, the computer executes 
a count loop to help find the y coordinate 
of the object. 

TWo counts are maintained, one runs 
continuously during the sweep and gives 

a measure of the time it takes to perform 
the sweep. The second count stops when 
the whisker detects a cylinder. The two 
counts are used to find out how far along 
the sweep the cylinder was detected. This 

Photo 5. One cylinder has already been located. The Photo 6. The whisker detects the cylinder. 
Movemaster arm is now using the single-whisker sen- 
sor to locate the second cylinder. 

distance is reduced by 1 cm to allow for 
bending of the whisker before contact is 
registered. Having found the xy coor- 
dinates of the point where the cylinder was 
detected, and allowing for the length of the 
whisker, the robot manipulator can be 
moved over the cylinder. 

In order to improve the accuracy with 
which an object can be located, the robot 
closes its grip on the object (pats it) to 
locate it in the x direction, and then opens 
its grip, rotates 90 degrees, and picks it up 
in the y direction. This maneuver locates 
the object in the gripper to better than 1 
mm. The cylinder is then stacked on the 
pile and the robot returns to the search 
at the place it left off. The stages of search 
and acquisition are illustrated in photos 5 
through 9. 

Conclusion. The system comprising sen- 
sor, interpolation algorithm, and search 
strategy work well and provide a fascinating 
demonstration of sensory feedback for a 
robot manipulator. Apart from the com- 
puter and robot arm, the demonstration 
cost very little and shows how even simple 
sensors can be used to good effect. 

Andy Russell is a lecturer in the Department of Elec- 
trical and Computer Engineering at Wollongong 
University in Australia where he lectures in digital elec- 
tronics and computers. His main research interest is 
in robotics— particularly in the area of tactile sensors. 

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Photo 7. The Movemaster pats the cylinder to ad- 
just its x-direction. 

20 ROBOTICS AGE April 1984 

Photo 8. The gripper picks up the cylinder in the 

Photo 9. The second cylinder is stacked on top of 
the First cylinder. 

Bipedal Balance 

Thomas A. Easton 
Box 705, RFD 2 
Belfast, Maine 04915 

A basic problem in the design of any 
legged walking machine is equilibrium, or 
balance. When searching for solutions to 
this problem, it is worthwhile to consider 
how living bipeds manage to stay on their 
feet. Then perhaps we can design a 
machine that works as well as a human, 
and in at least some of the same ways. 

For machines with four or more legs, the 
usual approach to balance is to program 
the leg movements so that three or more 
feet always remain on the ground. There 
can then always be a “polygon of support” 
enclosing the projection of the machine’s 
center of gravity on the ground. As long 
as this projection stays within the polygon 
of support, no matter how it wavers, the 
machine cannot tip over. Only when the 
polygon disappears— as it does in the faster 
gaits which put fewer than three feet on 
the ground at a time— must the machine 
use other ways to preserve equilibrium. 

Bipedal machines cannot always have a 
polygon of support. Even when merely 
walking, there must be times when only 
one foot is on the ground, and never are 
more than two feet on the ground. This 
does not mean that the machine must 
balance on one or two points. The feet can 
be flat and broad to provide a large sup- 
portive area. The machine must, however, 
keep the projection of its center of gravity 
within the limited “area of support” 
stamped out by one or two feet. 

This constraint is too limiting. Random 
disturbances inevitably shift the center of 
gravity out of the stable area. But more im- 
portantly, the center of gravity is forced to 
shift outside the stable area of support 
each time the machine shifts its weight 
from one foot to the other. The machine 
necessarily experiences tipping moments. 
How then can it stay upright? 

Animals commonly anticipate im- 
balances. That is, each footfall in a gait 
counteracts a tipping moment. This pro- 
duces a dynamic equilibrium, rather than 
a static equilibrium. Bipedal animals rely 

even more on corrective movements. They 
constantly counteract tipping moments, 
either by moving their feet or by shifting 
their centers of gravity. They do both so 
skillfully and smoothly that the corrective 
movements are rarely noticeable. Bipedal 
machines do neither very well. They seem 
limited to slow, careful, deliberate move- 
ments. Some must even keep both feet on 
the ground at all times, their motion 
limited to a slow, shuffling gait. 

A number of researchers are working on 
giving machines the capability for lifelike 
corrections and balance. Marc Raibert and 
his colleagues at the Robotics Institute of 
Carnegie-Mellon University in Pittsburgh 
have built a computerized pogo stick 
powered by compressed air. This one- 
legged “walking” machine hops all over 
their lab, and it keeps its balance quite suc- 
cessfully. Each time it lands, its computer 
measures just how far out of balance the 

Figure 1. The human brain and spinal cord. 

ROBOTICS AGE April 1984 21 

machine is. A servo then corrects any tip- 
ping moments with countertorques, taking 
advantage of friction between foot and 
floor. Some imbalances can be corrected 
by placing the foot out of the line of 
motion— by “propping” against a lean or 

Animals use both methods to correct 
their imbalances, but they don’t use a cen- 
tral computer to calculate and command 
corrective actions. Instead, they use a form 
of distributed control. They do not use the 
thinking or other high-level parts of the 
brain. They use reflexes , automatic motor 
responses to specific sensory stimuli, which 
are wired into low-level parts of the cen- 
tral nervous system. Many reflexes do not 
involve the brain at all. Instead, they re- 
quire only a few nerve cells in the spinal 
cord, that column of nervous tissue 
shielded by the backbone. 

The simplest reflex is the stretch reflex. 
It is a biological feedback circuit which 
holds a muscle at a particular, set length. 
This results in joints being held at specific 
angles. The stretch reflex depends on sen- 
sors buried deep within muscles. These 
sensors are the muscle spindles. Each mus- 

cle spindle is a bundle of modified muscle 
fibers enclosed in a tapered sheath. Motor 
nerves enter the sheath to control the spin- 
dle fibers, and sensory nerves leave the 
sheath to convey signals to the spinal cord. 

Motor commands from the spinal cord 
to a muscle reach both muscle fibers and 
spindle fibers, so that the two contract in 
parallel. As long as they remain in parallel, 
the spindle’s sensory nerves carry no 
signals. The spindle sensor’s zero point is 
set by its own contraction to match the 
degree of muscle shortening ordered by 
the nervous system. 

However, if the muscle is stretched 
beyond its “proper,” commanded length, 
the spindle is stretched beyond its zero 
point. The spindle then generates signals 
in its sensory nerves. These spindle signals 
report the degree and rate of change of the 
unintended stretch to the spinal cord. 
Motor cells in the spinal cord then com- 
mand the muscle to contract further and 
return to the initially set length. This is 
what happens in the classic knee-jerk 
reflex. The doctor’s tap on the tendon just 
below the knee cap stretches the thigh 
muscle beyond the length set by the ner- 

vous system. The thigh muscle’s spindles 
report the deviation to the spinal cord, 
whose cells then command the thigh mus- 
cle to contract. The contraction produces 
the typical reflex kick. 

The same thing happens when someone 
passes you a book. You hold one hand out, 
chest-high. When the book lands in your 
hand, the added weight causes your hand 
to sag. This motion stretches the biceps 
muscle which activates the spindles’ sen- 
sory nerves. The spindles report, and the 
spinal cord orders the biceps to contract. 
As a result, your hand rises to its previous 

The stretch reflex is also involved in 
maintaining erect posture. It helps the leg 
muscles keep the legs extended against the 
pull of gravity and the transient loads in- 
duced by the impacts of steps. It helps the 
muscles of torso and hips correct for sway 
and lean; it thus helps keep the projection 
of the body’s center of gravity under the 

A second important reflex appears in the 
flexion reflex. In its simplest form, it is a 
response to sensors in the skin. When 
these sensors register pain, they report to 
the spinal cord. Nerve cells there com- 
mand the muscles that bend or flex the leg 
to contract. The result is that the pained 
patch of skin is jerked away from the 
source of its agony. You see the flexion 
reflex in action when you step on a tack 
or touch a hot pot. Your foot or hand jerks 
away from the pain well before you con- 
sciously feel the pain. This demonstrates 
that the neural circuitry responsible for the 
reflex is local, in the spinal cord. It does 
its job while the pain signal is still on its 
way to the brain. 

What help is the flexion reflex in the pro- 
blem of balance? Because of the way the 
spinal cord’s nerve cells are wired together, 
the flexion reflex is generally accompanied 
by the crossed extension reflex. Even as 
one leg flexes, the other extends or stiffens. 
As the spinal cord sends commands to the 
flexor muscles of one leg, it also sends 
commands to the extensors of the other. 
It is as if fluid withdrawn from one 
hydraulic piston were supplied to another, 
so that the two pistons worked 180 degrees 
out of phase with each other. 

When a biped is standing on two legs, 
a flexion reflex can yank one foot off the 
ground. The accompanying crossed exten- 
sion reflex strengthens the support sup- 
plied by the other leg. If the biped is walk- 

Figure 2. The stretch reflex holds a muscle at a particular, set length. 
22 ROBOTICS AGE April 1984 

ing, and steps on a stone, the flexion reflex 
will try to yank the single foot on the 
ground into the air. The crossed extension 
reflex will get the other foot down in time 
to prevent a fall. 

Unlike the circuitry of the stretch reflex, 
where sensory nerves report directly to 
motor nerve cells, the flexion and crossed 
extension reflexes involve an intermediate 
nerve cell. The sensory nerves report to 
an intemeuron, which commands the 
motor nerve cells to activate the muscles. 
The existence of this interneuron means 
that higher levels of the nervous system, 
such as the brain, may also activate the 
pair of reflexes. This actually seems to hap- 
pen during locomotion; as one leg flexes, 
the other must extend. Reflexes may thus 
simplify the problem of motor control in 
general by reducing the number of 
separate actions the brain must coordinate. 

Skin sensors are also involved in the 
placing reflexes. They help the feet avoid 
holes and humps and find level ground to 
rest on. Humans have these reflexes, but 
they are more apparent in lower animals 
such as cats. To demonstrate this reflex, 
blindfold a cat and hold it in the air. Let 
the edge of one paw gently brush the edge 
of a table. The cat will lift the paw and 
place it squarely on the table. The cat does 
not need the highest levels of its brain to 
do this, for a cat whose cerebral cortex has 
been removed still has placing reflexes. 

The placing reflexes are well suited to 
establishing stable footing. The stretch 
reflex is used to hold a posture once it is 
set, and for correcting small deviations. 
The crossed extension reflex seems best 
for keeping a lurch from turning into a fall. 
Yet all can fail to keep a biped upright. 
Other reflexes must come into play. The 
most important of these other reflexes are 
the vestibular reflexes, whose sensors lie 
in the inner ear. 

The parts of the inner ear concerned 
with balance are the semicircular canals, 
the utricle, and the saccule. The semicir- 
cular canals are three hollow hoops set at 
right angles to each other and filled with 
fluid. At the base of each hoop is a bulbous 
ampulla. The ampulla is blocked by a 
gelatinous cupula in which are embedded 
the hairlike cilia of the sensory cells. Any 
rotation of the head in the plane of a hoop 
sets the fluid in the hoop in motion. The 
moving fluid deflects the cupula and bends 
the hairs of the sensory cells. As the hairs 
bend, the cells generate nerve signals 

which tell the nervous system which way 
the head is turning. 

The utricle and saccula also contain 
patches of sensory cells. These cells too 
have cilia, which are embedded in a 
gelatinous mass containing granules of 
calcium carbonate, the statoconia. The 
utricle and saccule respond to gravity and 
to linear accelerations, both of which act 
on the statoconia to bend the sensory cells’ 
cilia. The cells tell the nervous system 
which way the head is tipping or in which 
direction it is beginning or ending a 

The semicircular canals, utricle, and sac- 
cule are all basically accelerometers. They 
can easily be mimicked in a machine. They 
work together to maintain balance by trig- 
gering reflexes that compensate for leans, 

tips, spins, and falls. 

The vestibular reflexes can be demon- 
strated in a four-legged animal by standing 
the animal on a platform that can tip from 
side to side and from front to back. If the 
platform tips down in front, the animal’s 
forelegs extend and its hindlegs flex. If the 
platform tips down in back, the forelegs 
flex and the hindlegs extend. If the plat- 
form tips down to one side, the legs on that 
side extend and those on the other flex. 
All these motions tend to keep the body 
level. Other reflexes, which relate neck 
bends to vestibular stimuli and to limb flex- 
ion and extension, help keep the head 

The tippable platform is also useful for 
demonstrating the reflexes in humans. Peo- 
ple respond to a sideways tip by flexing the 

Figure 3. The flexion and crossed extension reflexes are useful for coordinating two legs. 

ROBOTICS AGE April 1984 23 

uphill leg and extending the downhill leg. 
During a forward tip, they lean backward; 
if the tip is extreme, the person may take 
a step, setting one leg forward, extended, 
while the other, now a hind leg, flexes. Peo- 
ple respond to a backward tip by leaning 
forward, or by stepping backward. In each 
case, the reflex keeps the body straight up 
and down and balanced on its feet. 

Humans also respond with their arms. 
When they tip to one side, they extend the 
arm on that side. When they tip forward, 
they flex both arms, bringing them up in 
front of the face. When they tip backward, 
they extend them backward. In each case, 
the reflex seems to prepare the body to 
catch itself in case the tip turns into a fall. 
Here, the reflexes seem to serve self- 
protection more than balance. 

Visual reflexes also help bipeds stay 
upright. The brain compares the visual 
field against the signals from the vestibular 
sensors and from pressure sensors in the 
soles of the feet. The brain can detect leans 
and sways just by changes in the orienta- 
tion of the visual field on the retina. The 
brain can maintain equilibrium by relying 
on vision alone, but vision seems less im- 
portant than the vestibular senses. That vi- 
sion plays a significant role is obvious when 
we are blindfolded or in the dark. Without 
the aid of vision, we are more likely to stag- 
ger. Yet the blind do without it quite well. 
In comparison, when the vestibular senses 
go awry, it can take a long time to learn 
to use vision alone. 

The various reflexes that contribute to 
balance inevitably interact, and balance is 
the result of their interplay. This interplay 
takes place at the level of the motor 
neuron, often called the “final common 
path,” which commands the individual 
muscles to contract. Various commands, 
including those for voluntary movements, 
reach the motor neuron along various 
paths. Some commands are strong. Some 
are weak. Some are excitatory. Some are 
inhibitory. The motor neuron sums them 
all and orders the muscle to contract only 
when the sum is above a certain level. 
Gradations in the strength of a muscle’s 
contraction arise because each muscle is 
commanded by a pool of many motor 
neurons. Since each neuron receives its 
own mix of commands, not all members 
of the pool order contractions at the same 
time, except in the case of the strongest 

The balance achieved by interacting 

reflexes is smooth and flexible. It is equal 
to the demands of walking, running, danc- 
ing, and carrying wine glasses full of 
nitroglycerin, even on rough ground. It 
does not distract the brain from other 

The living biped’s ability to balance is 
the envy of the roboticist. Yet it should be 
possible to build a legged machine that can 
move quickly, smoothly, and gracefully, and 
does not need all its brain to control its 
movements. The trick may be to imitate 
the methods of life. Have the central com- 
puter issue only a rough locomotor guide, 
a sequence of limb activations, or even a 
single activating command to a subsidiary 
control center. Give each limb its own con- 
trol circuitry, analogous to the neuronal cir- 

cuitry of the living biped’s spinal cord. 
Design this local circuitry to respond in set, 
corrective ways to the signals from sensors 
for limb configuration, gravity, accelera- 
tion, and “skin” pressure, and allow the 
signals to interact in determining the prop- 
er responses of the machine’s servos. 

The result will be a machine that uses 
reflexes. It will correct imbalances quickly 
and smoothly, and its computer will be free 
to handle other tasks. 

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Figure 4. The vestibular apparatus consists of the semicircular canals, the utricle, and the saccule. All are 
contained in the inner ear. 

24 ROBOTICS AGE April 1984 



T he 1984 Sensor and 

Transducer Directory is now 
available from the publishers of 
the monthly magazine, Sensors: 
The Journal of Machine Percep- 
tion. This is the first edition of 
an annual directory to be pub- 
lished every January. It contains 
more than 300 listings of com- 
panies which make hundreds of 
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26 ROBOTICS AGE April 1984 


Robot Warehouse 

Russ Adams 
3008 Mosby Street 
Alexandria, Virginia 22305 

A robot does not have to be a single 
piece of hardware. Sometimes it can be an 
entire building. Thke the device described 
in patent number 4,395,181 issued to 
Weston R. Loomer on July 26, 1983. The 
patent (owned by Litton Systems, Inc., 
Florence, Kentucky) discloses a system for 
automatically transporting loaded pallets 
around tracks in a warehouse. 

The automated warehouse storage sys- 
tem has a robot vehicle which transports 
loaded pallets along tracks. The vehicle has 
a main body and support wheels on each 
side. A lift mechanism raises pallets above 
the track level for transportation. The 
pallets can be lowered onto support sur- 
faces formed on the tracks for storage. 

The main vehicle body has a guide wheel 
at each corner. These guide wheels sense 
abrupt changes in the track’s direction 
before the load-bearing vehicle wheels 
reach that location. 

Power is supplied by a cable leading to 
a central power center. The cable is wound 
or paid out on a drum mounted to the 
vehicle’s chassis. This drum has a single 
helical groove which receives the cable. 

Figure 1 shows the automated storage 
system disclosed. The system is made up 
of a storage rack formed by horizontal rails 
( 11 ) and supported by vertical columns ( 12 ). 
Each pair of rails forms a storage bay along 
its entire length. The storage rack can con- 
sist of a single level or can be multitiered. 

The upper surfaces of each rail are de- 
signed to support loaded pallets. Each rail 
also has a lower surface ( 15 ) for suppor- 
ting the wheels of pallet-carrying vehicles 
( 20 ). The vehicle can, when empty, slide 
under pallets resting on the upper surfaces 
of the rails. 

Perpendicular to the pairs of pallet sup- 
porting tracks is another pair of rails. 

These rails form a pallet transfer track. 
Several pallet transfer carriages ( 30 ) move 
along the track. These transfer carriages 
each have an area for receiving the pallet 
vehicle and transporting a pallet. 

Electric power is supplied to the transfer 
carriage by a cable ( 32 ) attached to a cen- 
tral power source. Power is supplied to the 
pallet vehicle by another cable ( 33 ). This 
cable is wound around a drum mounted 
on the pallet vehicle. It is wound or paid 
out as the pallet vehicle moves along the 
pallet storage tracks. 

The transfer carriage movement and 
operation is controlled by a central logic 
system. This system also transmits com- 
mands to the logic system on board each 
pallet vehicle. 

As shown in figure 2, each pallet vehi- 
cle has a motor ( 21 ) for driving wheels ( 19 ). 
A second motor ( 22 ) operates the pallet 
lifting mechanisms ( 23 ) which raise and 
lower the pallets. 

Figure 4 shows the cable drum ( 34 ) with 
its helical grooves. The cable is wound on- 
to the drum along the grooves. This cable, 
in addition to carrying power, is also con- 
nected to the logic system ( 36 ). The drum’s 
construction automatically guides the cable 
into its proper position as the cable is 
wound. This eliminates complicated feed- 
ing mechanisms which might otherwise be 

When a pallet containing material needs 
to be retrieved, the appropriate pallet vehi- 
cle is given a command to move along the 
pallet supporting tracks to a location under 
the desired pallet. The location of the vehi- 
cle would be determined by tracking how 
much cable is left on the drum. When the 
correct location is reached, the vehicle’s 
lifting mechanism is activated and the 
pallet is lifted above the track surface. 

While the pallet vehicle is retrieving the 
pallet, the appropriate transfer carriage is 
moved to the end of the appropriate pallet 




Figure 1. The transport vehicles move along storage rack tracks. 

ROBOTICS AGE April 1984 27 

Figure 2. A close-up view of the transport and pallet vehicles. 

track. The pallet vehicle moves with the 
pallet along the track and into the space 
provided on the transfer carriage. The lift- 
ing mechanism is again activated and the 
pallet is lowered onto the transfer carriage’s 
pallet supports. The pallet vehicle slides 
out from under the pallet and off the car- 
riage. The carriage then transports the 
pallet to the front of the storage rack. 

Copies of this patent are available from the U.S. 
Patent and Trademark Office for $1.00 each. 
Orders for patents should be sent with payment 
to: Commissioner of Patents and Trademarks, 
Washington, DC 20231. 

The illustrations shown in “Patent Probe” are 
reproductions of diagrams in the original patent 

Reader Feedback 

To rate this article, circle the appropriate number 
on the Reader Service card. 

73 83 93 

Excellent Good Fair 

Figure 4. Helical grooves are built into the cable drum. These grooves automatically guide the cable into the proper winding position. 
28 ROBOTICS AGE April 1984 

Armega 33 

Part II: The Electrical Components 

The following sections discuss Armega 
33 ’s electrical and electronic aspects. 
These two aspects are intertwined in any 
actual sequence of arm movement and 

Power Supplies. All power for the Armega 
33 is provided by two regulated 12 VDC 
power supplies rated at 2.5 A for con- 
tinuous operation and having a 5 A surge 
capacity. One of the two units is dedicated 
to powering the servomotors. The other is 
used to power relays and the solid-state 
electronics. The two power supplies are not 
interconnected. Power required by in- 
dividual servomotors is normally less than 
1 A but may rise to more than 2 A in the 
case of extreme loads on the shoulder ser- 
vo. Combined maximum loads created by 
relays and integrated circuits may approach 
0.5 A. Separate power supplies ensure that 
fluctuations in power requirements from 
one source do not affect the other’s 

Manual Controls. There are two lessons 
which come very early in working with an 
arm driven by lead screw servos. First, you 
must have some method of manually con- 
trolling arm movement independently from 
the computer-based control system. Se- 
cond, you had better equip all moving 
elements with reliable limit switches. This 
is a useful approach for any kind of drive 
system, but it is vital for lead screw servos. 

Limit switches are required by those 
numerous instances in which either under 
manual or computer control, arm elements 
are inadvertently driven past their normal 
operating limits. In other types of drives, 
this may only mean a stalled drive motor. 
With lead screw servos it is much more 
likely to mean that something important 

D. F. Boyd 
5337 Taney Avenue 
Number 301 
Alexandria, VA 22304 

is either going to be bent or broken. The 
shoulder servo in Armega 33, for example, 
develops a thrust of up to 30 pounds (13.6 
kg) before it stalls. 

The only way the arm elements can be 
moved is by means of the servomotors. The 
servos lock the driven elements into place 
whenever they are at rest. This dictates 
some kind of manual switch console which 
will function conveniently even when the 
arm is completely disconnected from the 

The manual switch console I developed 
for Armega 33 is shown in photo 7. Each 
of the six switches controls one of the arm’s 
six servomotors. The single switch in the 
bottom row moves right and left and con- 
trols body rotation clockwise or counter- 
clockwise. The three switches in the center 
row move backward and forward and con- 
trol lifting or lowering movements of three 
arm elements: shoulder (left switch), elbow 

(center switch) and wrist pitch (right 
switch). The two switches in the top row 
both move right and left. The left-most 
switch controls wrist rotation, clockwise or 
counterclockwise, the right-hand switch 
controls opening and closing the hand. 
The 44-pin edge connector shown at the 
end of the manual console cable connects 
the console to the main circuit board and 
is typical of the connectors used to con- 
nect both the arm cable and the input/out- 
put board cable to the main circuit board. 

Figure 2 illustrates the power and con- 
trol elements associated with a “typical” 
servomotor. In a complete wiring diagram, 
these basic elements are essentially 
repeated six times over. The general ar- 
rangement of figure 2 is as follows. 

The manual switch console is shown at 
the lower left. It is connected to the main 
circuit board, shown at the center, which 
in turn is connected to an 8-bit parallel in- 

Photo 7. Manual control console. The arm can be easily switched from computer control to manual control. 

ROBOTICS AGE April 1984 29 

put/output board, shown at the right. Also 
connected to the main circuit board at the 
top is the wiring associated with a typical 
servomotor, in this case, the elbow servo. 
The major elements shown are connected 
to the main circuit board through 44-pin 
edge connectors so that all main com- 
ponents can be easily disconnected. The 
connecting cable for the manual switch 
console is 12 in. long (30.5 cm) and the 

cable to the input/output board is 60 in. 
long (1.5 meters). The wire bundle which 
emerges from the base component of the 
arm extends 16 in. (41 cm) from the base 
to the main circuit board. 

Double-pole/double-throw switches with 
a center-off position are used on the 
manual control box. The switches are used 
to reverse the polarity of the 12 V servo 
power at the motor terminals and thus 

reverse the servomotor’s direction of rota- 
tion. (Figure 2 shows only one typical 
switch of the six actual switches on the 
console). Although the simplest arrange- 
ment would require only two power leads 
to each servo, my design uses four power 
leads for each motor. The extra wires are 
required to make the limit switches operate 

The two limit switches which check the 

Figure 2. Typical servo power and control elements. This basic design is duplicated for each servomotor on the Armega 33 arm. 
30 ROBOTICS AGE April 1984 

forearm movement relative to the bicep are 
shown at the top of figure 2. The left switch 
interrupts the servo power when the 
foream reaches its maximum lifting posi- 
tion, the right switch cuts the power when 
the forearm reaches its maximum lower- 
ing position. Limit switches must do more 
than just stop all movement at the limit of 
travel. They must allow the servomotor to 
be reversed. The four-wire power lead ar- 
rangement permits this. 

Relay Servo Switching. Computer- 
controlled relays are used for switching ser- 
vo power. While a solid-state device could 
have been used, current flows in excess of 
2 A tend to complicate matters. Currents 
at this level pose no problems for relays. 

When the computer is in control of the 
arm, the B relay, shown near the bottom 
of the main circuit board in figure 2, 
operates as an almost exact counterpart of 
the manual console switch described 
earlier except that the relay has no center 
off position. Relay B is a double-pole/ 
double-throw relay with a 12 V coil. In the 
position shown in figure 2, relay B drives 
the elbow servo forward. For this servo, 
forward is in the lowering direction. When 
relay B is activated, the servo direction is 
reversed. Note, however, that the positive 
armature of relay B is not connected to the 
+ 12 V servo power source unless relay A 
is also thrown. Relay A is an identical 12 
V double-pole/double-throw relay which 
carries out two functions. When thrown, 
the left armature of relay A connects the 
-I- 12 V servo power source to relay B and 
at the same time closes the open circuit 
in one of the leads from the counter roller 
switch of the elbow servo. This permits 
counting pulses from the elbow servo to 
reach the input side of the 8-bit input/out- 
put board. 

Typical servo relay switching can be sum- 
marized as follows: to drive a servo for- 
ward , simply throw relay A; to drive a ser- 
vo in reverse , relays A and B must be 

Thus far, we have discussed most of the 
elements shown on the main circuit board 
in figure 2. The exceptions are the hom- 
ing relay C, the drive circuit for relay B, 
and the box which refers to figures 3 and 
4. We will explore these elements later. 

Computer Controlled Arm Movements. 
The 8-bit input/output board shown sche- 
matically at the right in figure 2, was pur- 

chased assembled. It is typical of digital in- 
terface boards available from a number of 
suppliers. The board accommodates one 
byte (eight bits) of output information from 
the computer and accepts one byte (eight 
bits) of input data. The particular in- 
put/output port number is set by means of 
an eight-position switch. The port chosen 
in this particular case was number three. 

When using the BASIC programming 
language (from a Radio Shack TRS-80™ 
computer), output commands to the inter- 
face board take the form of OUT 3,64. 
Commands to read input signals take the 
form A = INP(3). 

As indicated in figure 2, the 8-bit inter- 
face board is connected to the computer 
bus through a 40-conductor ribbon cable. 
Photo 8 shows the bottom side of the in- 
terface board. The two rows of eight tog- 
gle switches, one on each side of the board, 
were added to aid the manual testing of 
control logic and relays. Each pair of out- 
bit or in-bit contacts can be closed with 
a switch as well as through commands from 
the computer. The eight output bit posi- 
tions are in the row on the right side of 
the board with the nearest bit being bit 0 

and the most distant being bit 7. The in- 
put bit positions appear in the same order 
in the row at the left side of the board. 
When a binary 1 is sent to one of the out- 
put bits, it activates a reed relay which 
closes two contacts. Figure 2 shows that 
one contact of each output reed relay is 
connected to the +12 V relay and in- 
tegrated circuit power source. The other 
relay contact at out-bit 2 is connected 
directly to the coil of relay A. Accordingly, 
when the reed relay at out-bit 2 closes, the 
+ 12 V source is switched to the coil of 
relay A, relay A is thrown, and the elbow 
servo moves the forearm in the forward 

The BASIC command is simply OUT 
3,4. The binary equivalent of 4 is 
00000100. When this pattern is placed on 
the output byte, the third bit (bit 2) receives 
a binary 1. This closes the reed relay. 
Reversing the servomotor is slightly more 
complicated. If six of the eight bits are us- 
ed to switch each of the six servos forward, 
only two bits (bits 6 and 7) remain to con- 
trol all the reversing chores. To accomplish 
this requires some decoding logic. Figure 
2 shows that the individual leads from out- 

Photo 8. The 8-bit input/output circuit board is the interface between the computer and the arm. A total 
of 15 different control commands can be transmitted to the arm using only the eight output-bits (right side). 
Positive feedback, confirming all arm movements, is received through the eight input-bits (left side). 

ROBOTICS AGE April 1984 31 

bits 6 and 7 do not go to relay coils but 
instead to the box which references figures 
3 and 4. 

Figure 3 is titled Servo Reversing Logic. 
It is a simple logical decoder which per- 
mits out-bits 6 and 7 to reverse each of the 
six servomotors. The circuitry described 
decodes an 8-bit value into one of several 
operations. Reversing the body rotation 
servo requires a binary 1 at both out-bit 
0 and out-bit 6. Reversing the elbow ser- 
vo requires binary Is at out-bits 2, 6, and 
7. The computer-control, servo-command 
table is shown in table 2. 

The outputs of the AND gates in figure 
3 are labeled Reverse Body, Reverse Shoul- 
der, etc. However, the logic-level output 
from the AND gate is inadequate for acti- 
vating relay B. To provide enough cur- 
rent, the AND gate outputs are connected 
through amplifiers or drivers of the type 
shown at the lower right of the main cir- 
cuit diagram in figure 2. The driver circuit 
uses two transistors and provides more 
than enough current for relay B. 

Most of the preceding descriptions 
centered around figure 2 were based on 
the operation and control of a single serv- 
omotor. Armega 33 actually has six servo- 
motors. Photo 9 shows the completed main 
circuit board. TWo rows of six relays each 
are visible at the upper right of photo 9. 
Relays in the top row correspond to relay 
A in figure 2, and the bottom row to relay 
B. The small board just below the lower 
row of relays contains the driver circuits 
for each of the relays in the bottom row. 
The integrated circuits at the upper left of 
photo 9 include the two quad two-input 
AND chips used for the reversing logic 
represented in figure 3. 

Closed Loop Arm Feedback. The 
preceding sections have outlined the man- 
ner in which arm elements are driven in 
either forward or reverse directions under 
computer control. Not yet covered is how 
servos are stopped by the computer, and 
how the computer knows when to stop. 
Stopping a servo with a BASIC command 
is very simple. For example, if the program 
initiated a clockwise body rotation with an 
OUT 3,1 command, an OUT 3,0 com- 
mand will stop the motion. OUT 3,0 opens 
any A or B relays which are closed and 
thus halts all servo motion. 

The question of knowing when to stop 
takes us back to figure 2 and the function 
of the counter switches attached to five of 

32 ROBOTICS AGE April 1984 























AND CHIP (4801) 


Figure 3. Servo reversing logic. This simple digital decoding circuitry is used to activate the directional relays 
for the servomotors. 

the six servos. The counter switch for the 
elbow servo is shown at the top of figure 
2. It is a lever type switch with a small roller 
which rides on a two-lobe cam fastened to 
the servo lead screw. As a result, the switch 
contacts are closed twice during each lead 
screw revolution. One lead from the switch 
goes to a common connection joining one 
side of six of the input-bit positions on the 
8-bit interface board. The other lead is 
connected to one side of relay A and then 
to the input-bit 2 position on the interface 

board. When the two contacts of an input- 
bit position are connected, the computer 
reads a binary 1 in that bit position. 

Assume that the computer issues the 
command OUT 3,4. Relay A closes and 
the forearm is driven in the forward direc- 
tion. At the same time, since the counter 
switch circuit is also enabled by relay A, 
a binary 1 signal from the counter switch 
reaches the input-bit 2 position twice dur- 
ing each lead screw rotation. In between 
the switch closures the open switch 



Command Command 














OUT 3,1 



OUT 3,65 




OUT 3,2 



OUT 3,130 




OUT 3,4 



OUT 3,196 


Wrist Pitch 


OUT 3,8 



OUT 3,72 


Wrist Roll 


OUT 3,16 



OUT 3,144 




OUT 3,32 



OUT 3,224 


Other Commands 

Initiate Homing Mode OUT 3,128 10000000 

Terminate Homing Mode OUT 3,64 01000000 

Unassigned OUT 3,192 11000000 

T^ble 2. Armega 33 servo commands. 

registers as a binary 0. Since the binary 
1 occurs in the third bit position, the whole 
input byte is read as 00000100 (decimal 
4), each time the switch closes. 

The binary 1 pulses from the elbow ser- 
vo counter switch occur at the rate of about 
20 per second. In order to read these 
pulses, the computer must detect the 
change from a binary 1 to a binary 0. To 
ensure that none of the pulses are missed, 
the computer must scan the interface 
board input byte several hundred times per 

The BASIC program to accomplish this 
is relatively simple. Suppose that we want 
the forearm to move forward until the 
counter switch has produced 51 pulses, 
and then stop. (This is equivalent to 25 V 2 
rotations of the lead screw since there are 
two pulses per revolution). A BASIC 
program to accomplish this is shown in 
listing 1. 

Although the program in listing 1 pro- 
duces a forearm movement of 25 V 2 revolu- 
tions, it does not stop the movement 
precisely. The inertia of the rotating ser- 
vomotor, reduction gears, and the lead 
screw itself, causes the servo to coast for 
a fraction df a revolution. To stop the 

10 OUT 3,4 
20 A=INP(3) 

30 IP A=0 AND SW=1 THEN C1=C1+1 : 
SW = 0: GOTO 60 
40 IF A=0 GOTO 20 
50 IP A=4 THEN SW=1 
60 IP Cl =51 THEN 80 
70 GOTO 20 
80 OUT 3,0 

Listing 1. A BASIC program for moving the forearm 
forward until the counter switch has produced 51 
pulses. This is equivalent to 25 V 2 lead screw rotations. 
Cl is the cumulative count of pulses, SW is a pro- 
gram switch which can be set at 1 or 0. 

movement crisply and with almost no 
perceptible coasting, we can momentarily 
reverse the servo and then go to the 
OUT 3,0 command. To do this we can 
substitute and add the lines shown in 
listing 2. 

Line 80, instead of stopping the servo, 
now reverses it for a length of time deter- 
mined by the subroutine in line 1000. The 
program then proceeds to line 100 and 
issues the OUT 3,0 command to cut off 

80 OUT 3,196 
90 G0SUB 1000 
100 OUT 3,0 
1000 FOR N=1 TO 3800 
1010 NEXT N 
1020 RETURN 

Listing 2. Adding these program lines to listing 1 
reverses the servo power briefly when stopping mo- 
tion. This leads to a much more abrupt stopping 

servo power. The count of 3800 shown in 
line 1000 only represents a fraction of a 
second but will abruptly stop the forearm 
movement. I determined the appropriate 
braking delays empirically for each servo. 

The counter switch function and pro- 
gramming pattern outlined above is typical 
of all but one of the servos. The hand does 
not use a counter switch. Feedback signals 
from the hand indicate two conditions, fully 
open or fully closed. 


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ROBOTICS AGE April 1984 33 

Photo 9. The main circuit board includes servo switching relays and decoding logic. Toggle switches are 
for servo power supply, relay and integrated circuit power supply, and for switching servo power from com- 
puter control to manual control. The manual control console attaches to the main circuit board through 
a 44-pin edge connector. The arm cable attaches at top left and the input/output cable at top right. 

Photo 10. General test setup for Armega 33. The arm is shown in the home position. The shelf below the 
table edge contains, left to right: relay and integrated circuit power supply, servo power supply, ammeters 
for power supplies, manual control console and the main circuit board. The control computer, a TRS-80 
Model I, is at the right, with the input/output circuit board to the left of the keyboard. 

Homing the Arm. In order to carry out a 
series of arm movements, and then precise- 
ly repeat the sequence, an identical star- 
ting position for all arm elements is re- 
quired. This is defined as the index or 
home position. All control programs 
assume the arm starts in the home posi- 
tion. All servo pulse counts are calculated 
as displacements of each element from the 
home position. If there are any significant 
errors in attaining the home position, the 
subsequent arm element positions will be 
displaced from the desired position 
throughout the pattern of programmed 

It is possible, of course, to set the home 
position through manual control. However, 
this is tedious and time-consuming and 
cannot normally be done with the unifor- 
mity which can be obtained with computer- 
controlled homing. In addition, the arm 
cannot really be said to be under full com- 
puter control if it cannot carry out a pro- 
grammed sequence, index itself to the 
home position, and then repreat this se- 
quence as many times as desired. 

Photo 10 shows the arm in the home 
position. The base is rotated to the clock- 
wise limit, the bicep is at the full lift limit, 
the forearm is at the full lower limit, the 
wrist pitch is in the full lift position, wrist 
rotation is in the neutral position, and the 
hand is fully open. 

Photo 10 also shows a general view of 
the arm testing setup. The 8-bit interface 
board is in the aluminum case to the left 
of the keyboard. The shelf below the table- 
top contains (from left to right) relay and 
circuit board power supply, servo power 
supply, ammeters for each power supply, 
manual control console, and the main cir- 
cuit board. 

The homing control system utilizes some 
of the hardware features already discussed 
along with a number of new elements. An 
element which does double duty is one of 
the two limit switches which are installed 
on each arm element to stop movement 
when the maximum range of movement is 
reached. These limit switches were pre- 
viously described as a safety feature to pre- 
vent damage as a result of inadvertent con- 
trol actions. 

Referring to figure 2, note that the lower- 
ing limit switch is connected to a wire 
leading from the center switch terminal to 
the coil of relay C. When the elbow is 
driven in the lowering direction, the + 12 
V servo power supply is connected to the 

34 ROBOTICS AGE April 1984 

common terminal of this limit switch. 
When the arm reaches the limit of move- 
ment, the limit switch is thrown and cuts 
the servo current However, the limit switch 
is itself a single-pole/double-throw switch 
which switches the + 12 V to the center 
terminal and thence to relay C. This ac- 
tivates relay C which, in turn, connects the 
two contacts for input-bit 5 on the inter- 
face board and presents a binary 1 at that 
position. The resulting input byte is 
00100000 which is read by the control pro- 
gram as decimal 32. 

As a result of this sequence of events, 
the computer detects a decimal 32 value 
at the input byte when the forearm reaches 
its home position. This is an important ele- 
ment in the homing sequence. The arm 
elements are driven to their home posi- 
tions one at a time so that input-bit 5 can 
be used to detect the arrival at the home 
position for all six arm servos. This is also 
the method by which feedback from the 
hand is obtained during normal operation. 
When the command OUT 3,224 is given 
to open the hand, the control program 

monitors the input byte until a 32 is de- 
tected. This indicates that the hand is ful- 
ly open. The same is true for closing the 

The homing control system involves 
some additional digital logic and some ad- 
ditional power switching relays. The added 
logic is required because still another 
burden is placed on out-bits 6 and 7. In 
addition to handling the servo reversing 
chores previously described, out-bit 7 is 
now used to establish a homing mode, and 

out-bit 6 is used to restore the normal 
operating mode after homing is completed. 
Figure 4 contains the additional logic and 
relays involved in the homing control 

Remember that when the servo motion 
was reversed, out-bits 6 and 7 were always 
activated in combination with one of the 
A type relays. In the case of homing, we 
want the homing mode activated when 
there is a binary 1 only in out-bit 7 loca- 
tion, i.e., 10000000 (decimal 128). The 

return to normal mode will be triggered 
by out-bit 6 alone, i.e., 01000000 (decimal 

There are two basic reasons why the arm 
must be placed in a special mode to com- 
plete the homing sequence. First, the limit 
switches are never activated during normal 
operation. They are present only to stop 
inadvertent attempts to drive the elements 
past their normal limits. The arm elements 
move at a significant rate of speed (up to 
0.7 radians per second) and crashing into 



Figure 4. Homing logic and control elements. This circuitry is used to determine when the hand and arm has reached the home position. The logic gates shown 
in this diagram consist of a 4071 two-input OR gate, a 4049 two-input AND gate, and a 4069 hex inverter. All logic components are CMOS. 

ROBOTICS AGE April 1984 35 


510 CLS : OUT 3,0 
520 OUT 3,128 
530 GOSUB 10000 


545 OUT 3,1 
550 A=INP(3) 

560 IF A>16 THEN 580 
570 GOTO 550 

580 PRINT @ 338, "BODY IS HOME" 

585 OUT 3,2 
587 GOSUB 10000 
590 A=INP(3) 

600 IF A>16 THEN 620 
610 GOTO 590 


625 OUT 3,4 
627 GOSUB 10000 
630 A=INP(3) 

640 IF A>16 THEN 660 
650 GOTO 630 

660 PRINT 0 466, "ELBOW IS HOME" 

665 OUT 3,8 
667 GOSUB 10000 
670 A=INP(3) 

680 IF A>16 THEN 700 
690 GOTO 670 


705 OUT 3,16 
707 GOSUB 10000 
710 A=INP(3) 

720 IF A>16 THEN 740 
730 GOTO 710 


745 OUT 3,224 
747 GOSUB 10000 
750 A=INP(3) 

760 IF A>16 THEN 780 
770 GOTO 750 

780 PRINT 0 658, "HAND IS HOME" 

785 OUT 3,0 
790 OUT 3,64 
800 GOSUB 10000 
810 OUT 3,0 

830 GOSUB 12000 


10010 FOR N=1 to 985 
10020 NEXT N 
10030 RETURN 

12010 FOR N=1 TO 12850 
12020 NEXT N 
12030 RETURN 

Listing 3. The BASIC Homing sequence program. This program, which is run at the beginning and end 
of most control sequences, ensures that the arm is always placed in a known starting position. 

a limit switch at full tilt involves at least 
a minor degree of violence. Conversely, the 
homing mode deliberately drives each arm 
element to the point where it is stopped 
by a limit switch. Accordingly, it is desirable 
to reduce the normal rate of movement 
when in the homing mode. 

The second special homing requirement 
is the need to enable the wrist rotation 
limit switch. This limit switch is normally 
disabled during arm operation since it may 
be desirable to rotate the hand as many 
as six revolutions without interruption. 
When going to its home position, however, 
wrist rotation must be accurately stopped 
at a known position. This is permitted by 
enabling the limit switch during homing. 

The upper portion of figure 4 shows the 
digital logic elements of the homing 
system. Relays and electronics are shown 
in the lower part. The digital logic consists 
of seven OR gates, four AND gates, and 
three inverters. This decoding logic detects 
the occurrence of a binary 1, only at out- 
bit 7, or only at out-bit 6. (The logic also 
recognizes the occurrence of 6 and 7 on- 
ly, but this is not being used at present.) 
Referring to command list in table 2, we 
see that binary Is are constantly recurring 
in out-bits 6 and 7 during servo reversals. 
However, they always occur in combination 
with one or more additional out-bit posi- 
tions. As long as this remains true, the 
homing mode will not be triggered by out- 
bit 7 in combination with a 1 in any other 
bit. Out-bit 7 in isolation however, (equiva- 
lent to decimal 128) produces a binary 1 
at the output of the final AND gate. This 
signal, when amplified through a driver cir- 
cuit, throws relay D a four-pole, double- 
throw relay. 

The four circuits thus closed perform the 
following functions: 

1. A 10 ohm, 10 W resistor is added 
in-line to the power supply line from the 
servo power supply. This slows down the 
speed of all arm elements during the 
homing sequence. 

2. The wrist rotation limit switch is ac- 
tivated. As a result, wrist rotation is stop- 
ped in the neutral position during 

3. The homing limit switches of all arm 
elements are connected to relay C. This 
is the same relay which provides the 
hand feedback signals during normal 
operation, and which produces a binary 
1 at in-bit position 5 on the interface 
board, when it is thrown. 

36 ROBOTICS AGE April 1984 

4. Relay D is latched in the thrown 
position until the homing sequence is 
complete. Upon completion, the control 
program places a binary 1 in the out-bit 
6 position (equivalent to decimal 64) 
which throws relay E, unlatches relay D, 
and thus terminates the homing mode 
and restores the normal operating mode. 
The homing control program for 
Armega 33 is given in listing 3. Line 520 
issues the command OUT 3,128 which 
places the arm in the homing mode. The 
GOSUB 10000 command in line 530 pro- 
duces a very short delay, about 0.01 
second, to give relay D time to latch. Line 
540 places a message on the video display 
which indicates that the homing sequence 
is underway. Line 545 starts the base rota- 
tion servo in the clockwise direction. Lines 
550 through 560 keep scanning the input 
byte of the interface board until a number 
greater than 16 appears. When this hap- 
pens, the computer displays “BODY IS 
HOME” on the video display. 

Line 560 seeks a value greater than 16 
to ensure that the value being read at the 
input byte is a result of the closure of relay 
C. When the OUT 3,1 command is given 
to start the base clockwise, the pulse 
counting for the base servo which puts a 
series of binary Is and 0s in the in-bit posi- 
tion 0 is also activated. Similarly, all of the 
other counter circuits are activated during 
homing and generate pulse signals. The 
highest value from this source will be 16 
(from the wrist rotation counter). A value 
greater than 16 indicates that the homing 
relay has been thrown and that the element 
is home. 

The program in listing three repeats the 
above outlined process, in turn, for each 
body servo: the shoulder (lifting direction), 
the elbow (lowering direction), wrist pitch 
(lifting direction), wrist roll (clockwise 
direction) and hand (fully open). Upon 
completing the homing for each element, 
a message is written on the video display 
so that the entire series can be traced. 
After the hand reaches the home position, 
line 785 opens all servo switching relays 
with an OUT 3,0 command and line 790 
executes an OUT 3,64 which throws relay 
E, unlatches relay D and terminates the 
homing mode. The GOSUB 12000 in line 
830 is a 3 second delay loop which retains 
the video display long enough to be read. 

The end result of all of this activity is 
to reliably and accurately place the arm in 
the home position portrayed in photo 10, 

starting from any configuration that the 
arm may have been in when the homing 
sequence was activated. In all operating 
control programs for Armega 33, the hom- 
ing sequence appears both at the begin- 
ning and the end of the program. Despite 
the lengthy explanation, the actual hom- 
ing procedure typically requires only a few 

Returning to photo 9 (the main circuit 
board) we can now identify the remaining 
features. The integrated circuits at the up- 
per left include two quad two-input OR 
chips, one hex inverter chip and one quad 
two-input AND chip for the homing logic. 
This is in addition to the two AND chips 
previously identified for the reversing logic. 
The large relay at the lower right is the 
homing mode relay D. The small relay just 
below it is the unlatching relay E and the 
small relay at the extreme lower right is 
relay C. The remaining small relay was not 
shown in figure 4 and simply throws in 
parallel with relay D to route all the hom- 
ing limit switch leads to relay C. 

The 10 W resistors along the lower edge 
of the board include the homing slow-down 
resistor of figure 4. The additional large 
resistors could be described as servo tun- 
ing resistors, which have been inserted in 
the servo power leads to provide a power 
voltage drop for the small servomotors and 
a differential voltage for the lifting and 
lowering power leads to the shoulder, 
elbow and wrist pitch servos. The shoulder 
servo, for example, has to lift the weight 

of almost the entire upper arm when lift- 
ing, even without a useful load, whereas 
the same weight tends to drive it down in 
the reverse direction so that it runs 
noticeably faster. By placing a resistor in 
the lowering power lead, an almost uniform 
speed of movement in both directions can 
be attained even with substantial loads. 
Jacks at the upper left of the main circuit 
board are used for connecting the leads 
from the two power supplies. The three 
switches at the lower left provide servo 
power on and off; relay and integrated cir- 
cuit power on and off; and selecting 
whether the servo power is connected to 
the manual control console, the circuit 
board relays, or off. 

Electronics Summary. Although a large 
amount of actual components are used in 
the overall control electronics, the actual 
design is relatively simple and straight- 
forward. Elementary logic circuits are used 
to determine the arm motions and modes. 

Next month concludes the Armega 33 
construction details by describing the con- 
trol computer and the operating programs. 

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ROBOTICS AGE April 1984 39 

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Circle 25 



Home Robot Available 

T /iihotirs of Carlsbad, California, has 
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Also included is a personal computer, part 
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detachable keyboard, optional printer and 
5Va inch floppy disk drive. 

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module, Hubot speaks in a real voice with 
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cludes a microphone and enables owners 
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trols the robotic functions. Hubot moves by 
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His rotating OSP (Obstacle Sensing Pro- 
cessor™) collar alerts him to stop when he 
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months include a burglar and fire alarm, 
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Hubot’s battery is recharged by plugging 
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enable Hubot to detect when his battery is 
low and automatically recharge himself at 
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Circle 40 

IBM-Compatible Video Capture System 

new IBM-PC/XT™ compatible video 
capture system, designed for OEM 
graphic arts systems, is capable of directly 
digitizing such source materials as black- 
and-white and color art and photography in 
the form of film and prints as well as line 
art, Velox or engineering drawings, mechani- 
cal parts, textiles, paper, and X-rays. The up 
to 640 by 512 pixels resolution permits high- 
quality pictorial data to be stored in digital 

form. The system can retrieve and display 
the information in 16 levels of gray values, 
convert it into pseudo-color or manipulate 
it to enhance specific characteristics. 

Applications may include graphic image 
processing for art studios, slide presenta- 
tions, image analysis and data reduction, 
feature recognition, computer-aided color, 
and pattern generation. 

Software support is offered for printer out- 

put, annotation, storage, comparison, com- 
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ly under development. 

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PC-EYE Marketing.) Circle 41 

ROBOTICS AGE April 1984 41 



Seam Finder 

JK laser-operated, arc welding seam 
XJ. finder system, introduced by ASEA 
Robotics, Inc., consists of an optical laser 
sensor and microcomputer, interfaced with 
an ASEA S2 Controller and an IRB 6AW/2, 
IRB L6AW/2 or IRB 60/2 electric robot The 
seam finder is designed to interface with 
ASEA’s new Sorbit robotic arc welding soft- 
ware package. The system can be used in 
most arc welding, resistance welding, and 
plasma-arc cutting applications, particular- 
ly those situations involving thin sheets (as 
small as 0.03 in), short welds, and quick cy- 
cle times. 

The optical sensor has a resolution of 
0.002 in., a measurement distance of 6.900 
in. and a width range of 1.300 in. Search 
position accuracy is ±0.016 in. 

Searches can be performed in either two 
or three dimensions in roughly 1 to 1.5 
seconds without the arc being actuated. 
Weld parameters can be automatically ad- 
justed to accommodate variations in the 
weld seam. 

For more information, contact: Joseph 
Bianco, Manager, Marketing Services, ASEA 
Robotics Inc., 16250 West Glendale Drive, 
New Berlin, WI 53151, telephone (414) 
785-3400. Circle 42 

Digital Servo System 

ALIL of Mountain View, California, 
has announced the availability of a 
digital servocontroller distributed as either 
chip sets (GH000 and GL-2000) or a com- 
plete STD Bus card (DMC-100). The con- 
troller governs torque, speed, ramp-up, 
ramp-down, limits, cycle time, and other 
aspects of a servo system. 

The DMC-100 also include; a digital filter 
which stabilizes the position loop and does 
not require velocity feedback transducers. 
The filter coefficients may b€ continuously 
changed by the host computer, making the 
system applicable for robotics and 

The chip set, GL-1000 and GL2000, and 
the DMC-100 are fully programmed; the user 
need only command the desired movements 
and actions from a host terminal or com- 
puter. The GL-1000 interface 1C is available 
independently for those users who prefer to 

program their own controller. The chip pro- 
vides position feedback decoding and motor 

An application note is also available that 
describes the DMC-100 in detail and il- 
lustrates the step-by-step procedure for 

utilizing digital servo. 

For more information, contact: Dr. J. Tkl, 
GALIL Motion Control, 49 Showers Drive 
#G442, Mountain View, CA 94049, tele- 
phone (415) 948-6551. 

Circle 43 

42 ROBOTICS AGE April 1984 





High Tech from 
Down Under 

F lexible Systems, manufacturers of the 
Thsman Turtle and TUrtle Tot, will 
shortly release a research-oriented manipu- 
lator designed by Robotnick P/L of Austra- 
lia. The arm, recently featured at the Las 
Vegas Comdex Computer Show, utilizes an 
open structure allowing user modification. 

The arm has five axes of movement, plus 
gripper action driven by base-mounted 
bilevel stepper motors, providing high step 
rates at full power for maximum perfor- 
mance, and trickle currents for holding 
torques at zero step rates. Pickup payload 
is 1 kg at its full extension of 750 mm (27.5 
in.). Software is available for the Apple, the 
IBM PC, and CP/M-based machines, as well 
as a Z80-based controller that can operate 
as a slave computer or standalone con- 
troller/development system. 

For more information, contact: Harvard 
Associates, Inc., 260 Beacon Street, Somer- 
ville, MA 02143, telephone (617) 492-0660. 

Circle 44 

High Force-to-Weight Ratio 

lightweight, RS-232-compatible, 
pneumatic servo gripper that inter- 
faces directly with Puma robots is being in- 
troduced by Flexamation Robotics Systems 
of Johnston, Rhode Island. 

The Flexamation PSG-1 Pneumatic Ser- 
vo Gripper, priced from $4,900, features a 
maximum gripping force of 100 lbs., but 
weights only 2.15 pounds. Providing less 
than one second positioning time with 
±0.02 inch repeatability, the gripper opens 
a full 2.75 inches and has optical cross-fire 


sensors in the fingertips for workpiece detec- 
tion. It has pointed tips for bin picking and 
an adjustable overload sensor in the base, 
with spring compliance for safety. A com- 
plete system consists of a 13.25 by 9 by 7.75 
inch controller, the gripper, and related 

For more information, contact: Flexama- 
tion Robotic Systems, David A. Martino, 
Engineering, 14 Harrington Drive, Johns- 
ton, RI 02919, telephone (401) 944-2242. 

Circle 45 

Memocon Crawler 

CVock Model Parts of New Hyde Park, 
New York has introduced a program- 
mable robot kit with applications to school 
science projects, robotics courses, or per- 
sonal enjoyment. The robot includes an on- 
board programmable CMOS 256 word by 
4 bit sequencer which can be programmed 
through any popular microcomputer having 
a parallel interface. The attached teach pen- 
dant can be used to program the robot to 
go forward, go right, go left, pause, sound 
a buzzer, light an LED lamp, or repeat a 

program continuously. The three-wheeled, 
5V2 in. diameter robot known as Model 

4Z6-918 Memocon Crawler is offered for 
$79.95 in kit form with four pages of easy- 
to-follow mechanical assembly instructions. 
All electronic elements are contained in two 
presoldered and pretested printed circuit 
boards. Power is supplied by one 9V and 
two A A batteries (not included). 

For more information, contact: Stock 
Model Parts, Division of Designatronics, 
Inc., 54 South Denton Avenue, New Hyde 
Park, NY 11040, telephone (516) 328-3333. 

Circle 46 

ROBOTICS AGE April 1984 43 



Vision System 

for Industrial Inspection 

C ognex Corporation has announced its 
newest product, Checkpoint?* 1 a 
sophisticated vision system for industrial in- 
spection. Checkpoint is a flexible system 
which the user can easily teach to perform 
a wide range of inspection and quality con- 
trol tasks such as: label inspection; print 
quality inspection; keycap inspection; and 
printed circuit board inspection, including 
lead sensing, component placement, and 
component verification. 

The basic Checkpoint system consists of 
four hardware components (the Checkpoint 
processor, a camera, monitor and keyboard) 
and Cognex’s proprietary software for im- 
age acquisition, analysis, and storage. This 
basic system can be used in any inspection 
task that requires checking the presence/ 
absence, shape and positioning of a well- 
defined item such as a part, a product label 
or a string of etched or printed characters. 

Checkpoint eliminates the subjectivity 
associated with human visual inspection and 
performs its inspection tasks with objectivity, 
accuracy, and consistency of results. It also 
eliminates the need for sampling. The 
system can provide 100 percent product 

For more information, contact: Mary E. 
Doyle, Cognex Corporation, 72 River Park 
Street, Needham, MA 02194, telephone 
(617) 449-6030. Circle 47 

Tactile Sensor System 

arry Wright Corporation of Water- 
town, Massachusetts has developed a 
low profile, compliant touch sensor that pro- 
vides force, position, and orientation feed- 
back. This touch sensor, the TS 402 Tactile 
Sensor System, consists of one sensor pad— 
P/N TS 402-PI and one interface device— 
PIN TS 402-D1. 

The sensor yields an array of 256 in- 
dividual data points, with a point-center-to- 
point-center distance of 0.1 in. An electronic 

interface is available which operates with a 
5V input and 5V output. The output is ex- 
pressed as an 8-bit digitized signal. An in- 
tegrated microprocessor/interface device is 
available as an option. 

For possible field testing of the system by 
qualified Robotics/FMS applications, and for 
more information, contact: Barry Wright 
Corporation, 700 Pleasant Street, Water- 
town, MA 02172, telephone (617) 923-1150. 

Circle 48 


C^astem Machinery and Manufacturing, 
Jjj Inc. of Salt Lake City, Utah has an- 
nounced the availability of Q-Bots— kits of 
robotic components whose basic concept is 
education. Q-Bots are teaching tools de- 
signed to show by instruction and experi- 
mentation how electromechanical devices 
work, prototyping real work applications. 

A kit includes eight motor assemblies, two 
power wheel assemblies, two light sensors, 
two magnetic sensors, one claw assembly, 
and the necessary bases, wheels, and parts 
for building a variety of functional robots. 
The clear and concise instruction manual 
explains how to build a mechanical arm and 
an automated cart that utilizes light sensors 

Circle 49 

to follow a white line, and how to automate 
a vacuum cleaner. The cost is $500.00 per 

Q-Bots introduces the home computer 
user to robotic and electromechanical 
devices. Any personal computer can inter- 
face with Q-Bots over an RS-232 printer 
port. The computer stores and executes the 
programs needed to direct or cue the robots. 

Users are encouraged to experiment and 
to develop add-ons in both software and 
hardware for possible inclusion with the kits. 

For more information, contact: Carol M. 
Meyers, president, Communications Net- 
work, 6477 Telephone Road, Suite 551, Ven- 
tura, CA 93006, telephone (805) 644-0400. 

44 ROBOTICS AGE April 1984 


Artificial Intelligence. These are 
the buzz words of the eighties. The 
words of an exciting, new world. 

To learn about robotics, you 
must do more than read, you must 

Where can you find in-depth in- 
formation about affordable robotic 

Though several industrial robot 
directories already exist, no direc- 
tory has yet been published which 
describes the inexpensive equip- 
ment available for use with per- 
sonal and modular, board-level 
computers. Until now. 

The Sourcebook 

The 1984 Robotics Age Product 
Guide: A Sourcebook for Educators 
and Experimentalists , is packed with 
hundreds of descriptions containing 
vital information about inexpensive 
robotics products. The Robotics 
Age Product Guide is essential 
reading and research material for 
all educators, research and develop- 
ment engineers, and experimenters. 

Product Guide listings run the 
full gamut of robotics products: 
self-contained robots and robotic 
arms, turtles, vision systems, 

Robotics Age 
Product Guide: 

A Sourcebook for 
Educators & Experimentalists 


speech generation and recognition 
products, robot control languages, 
personal robot peripherals and 
ultrasonic ranging systems. No 
other publication can bring you the 
same in-depth information. 

The Product Guide delivers 
useful descriptions, names of 

contact people, and product 

Intelligent machines are part of 
our daily lives. Stay in the forefront 
of this new technology. Read the 
1984 Robotics Age Product Guide: A 
Sourcebook for Educators and 

Available in March for $9.95 

Robotics Age Product Guide 

174 Concord Street 

Peterborough, NH 03458 
or give us a call at (603) 924-7136. 

ONLY $9.95 

□ Please send . 

copies of the 1984 Robotics Age Product Guide 

at S9.95 (includes postage and handling costs). Total Enclosed $ 

Overseas orders please add $8.00 for airmail postage. 
□ Personal Check □ Money Order □ MasterCard □ Visa 

Account No. 



Name (Please Print) 







Send to Robotics Age 

174 Concord St., Peterborough, NH 03458 (603) 924-7136 

" I 

4/84 RA 



The Most Sophisticated Personal/Educational Robot Available 



Processor - Mo- 
torola® M 68000 16 
brf microprocessor 
System Memory - 128K 
bytes RAM expandable 
to 5I2K byte on board, ex- 
pandable to 8M byte by S-100 
board ROM up to 16K bytes 
System 10 2-RS232 serial ports 
one-parallel port. These are for 
communication with the outside 
world, internal communications be- 
tween servos and computer are taken 
care of directly. 


Anthropomorphic design sculptured body skin adds a finishing touch to the 
fully machined aluminum inner structure. 

each with: 
Axis One: 
Shoulder is 
thru 135°. The 
motion you use 
while bowling. Axis 
Two: Shoulder is pow- 
ered thru 105°. The mo- 
tion you use doing jumping 
jacks. Axis Three: Upper arm 
is powered thru 135° of rotation 
The motion you use while arm 
wrestling. Axis Four: Elbow is po- 
wered thru 115°. Axis Five: Wrist is 
powered thru 90°. Axis Six: Gripper 
opens up to 2*4 inches and closes down to 
zero. All arm servos are powerful enough 
to enable ‘MARVIN’ handling a minimum 
five pounds load in each gripper. (A six 
pack of your favorite beverage weighs 
approx. 4*4 lbs.) 

In addition to the 12 arm axes, ‘MARVIN’ 
has: Neck is powered thru 180° rotation. 
Waist is powered from straight up to 50° 
forward. This enables him to reach the 
floor with his grippers. 


Expansion Bus - 8 slot S-100/EEE-696 ex- 
pansion bus. Intelligent Servo Controller - 
Resident on the expansion bus is one S-100 
card with 16-full 4 quadrant power MOSFET 
pulse width modulated servo controllers with 
axis feedback and auto refresh. 

This Iowa Precision Robotics Ltd. Model 68- 
100 computer supports CP/M® 68 K and 
Forth operating systems. It is also used 
in our industrial Robot Controller 
where it meets exacting 


Drive Wheels: Each drive wheel is an 
individual servo to enable direc- 
tional control. His maximum 
rate of forward speed is 50 
inches per second and he 
has enough power to 
climb a 10° incline. 

The MARVIN MARK I is ready NOW! We would like to cordially invite you to 
see MARVIN MARK I at the International Personal Robot Congress and 
Exposition, April 13th thru the 15th at Albuquerque Convention Center, Albuquerque, 

New Mexico. This will be a unique opportunity to research the educational robot market in one 
location. We are positive when you see MARVIN MARK I and compare his advantages to other 
personal robots you will want to take him home. 

MARVIN MARK I has many outstanding features that set him apart from all other educational robots. 

1. 68000 CPU based on board computer/state of the art. 

2. S-100 Expansion Bus-a standard feature. 

3. CP/M compatable. 

4. Two 6 axes Arms - 5 lbs. payload per arm. 

5. Simultaneous use of ALL Axes - allows both arms to work on coordinated tasks. 

6. Variable speed and direction on ALL axes. 

7. Park MARVIN MARK I anywhere and you have a mobile, blackout proof, personal computer 
with a disk drive and more capabilities than most business computers. 

8. The list goes on and on. 

The best news is MARVIN MARK I’s price! $5,995.00! MARVIN MARK I cost less than comparable business computers with the 
same capabilities and you get the state of the art in educational robots, MARVIN MARK I as a bonus! 

Order today to avoid delivery delays as orders are piling up and 1984 production is limited. A color brochure is available for more information. 


/owa .Precision Pobotics, Ptd. 

908 10th Street, Milford, Iowa 51351 
Phone: 712/388-2047 or 712/338-2349 
Circle 8